Balance is fine but...
1) many DMs enjoy the rules as a pseuso-naturalistic physics engine. In such context, "balance" can only appear as an external metagame consideration.
2) D&D has a pretty heavy tradition of naturalism trumping protagonism
On that basis, we need to seriously revisit damage done by ranged weapons, including the armor penetration of an English longbow, don't we? Weapon damage in general, really - a knife strike is perfectly capable of killing a healthy person.
3) I don't believe in achieving "balance" in a context where Fly/Scry/Fry effects are appearing on the Mage spell list at legacy levels. Because of the Compatibility objective, Next can't be balanced. The unfortunate decision of allowing 3e free multiclassing (which constrains each and every level of each and every class to be balanced against each other) creates expectations that can't be fulfilled.
I find multiclassing its own special challenge which must be addressed separately, however perhaps balance requires we use a different multiclassing approach, such as a level adjustment for having one or more additional classes, rather than a straight level for level mechanism. That's a whole different thread(s). Similarly, I think the answer to fry & scry is to restrict the movement aspect. I am still, however, waiting for someone to provide me a (3e) by the rules fry & scry tactic that works at medium levels. Typically, one or more of the following are ignored:
- Teleport requires "You must have some clear idea of the location and layout of the destination.", while Greater Teleport needs " In addition, you need not have seen the destination, but in that case you must have at least a reliable description of the place to which you are teleporting. If you attempt to teleport with insufficient information (or with misleading information), you disappear and simply reappear in your original location." How much information is needed, and how do you get it?
- you can get up to "Studied carefully" by scrying
for no less than an hour
- Scry requires knowledge of the target as well. If they save, it fails for the next 24 hours. And it targets a person, not a location.
- Scry gets the target and "about 10' in all directions" - is that enough to target the Teleport? You must arrive (all of you!) within 10' of the fellow?
- If he moves, your Scry moves - you scry on a person, but you need to study a location.
- Scry lasts a minute per level - how do you study an area for an hour? Greater scry lasts an hour per level, but now we're talking a 7th level spell.
There are also easy fixes to Scry & Fry. Give Scrying and/or Teleport longer casting times, making them more ritualistic. Explicitly remove the ability to teleport to a location based on scrying a person (or based on scrying at all). Add a "stunned for one minute after transport" result to Teleport, as you need a bit of time to reorient yourself - if you're just using it for long distance transit, that's not a big deal, but if you have ten rounds between arrival and being combat-capable, this is nowhere near as effective. This could be stunned, unable to concentrate (no casting), nauseous, etc. Maybe its worse for locations you are less familiar with. Make Teleport just a bit less precise - for example, perhaps you arrive somewhere within 100' of your intended destination, not with a precision level measured in inches.
If your carefully studied area requires you to view a 100' x 100' area for no less than an hour, randomly places the caster at a point within that area and leaves all Teleported Stunned for 1 minute, how effective is Scry & Fry? Still too effective? Add "cannot concentrate for 5 minutes". It can be balanced. To my mind, Teleport is the problem - it should be for long distance transport, and leaving the teleporters incapable of combat immediately after teleporting effectively restricts it to that usage.
And the big one - enemies who use the same tactics. That tends to get players more interested in fixing the abuses, whether by a different interpretation or an outright rules change.
By the way, I am personnally torn between naturalism and protagonism. One-trick ponies are obnoxious, but those profiles do exist in real life, and are even archetypal. Should they be banned for meta game reasons ?
Name a few from fiction we are trying to emulate. As PC's, they must be main characters, not sidekicks or briefly appearing characters. Often, those characters who appear initially to be one trick ponies, but have enough popularity to reappear as more than plot devices, tend to get fleshed out and aren't one trick ponies as they grow into being protagonists.
Oh, and if we want to argue "one trick ponies are common in the fiction, so they should be in the game", splitting the party is pretty much universal in fiction, isn't it? There are differences between the various media, and games are their own media. Vast power disparities in character experience/level are pretty common in the source material too. Who gets to start play as the L17 Mentor, and who starts as the L1 (or not even L1) apprentice?
We're playing a mishmash game of CnC, BECMI, and AD&D. The guy who did most of the mashing isn't exactly up on modern balance tech (as an grognard, he feels that's all new school <derogative>). For example, he doesn't want to understand that a +2 to AC (or other defense) is worth more than a +2 to hit. Unsurprisingly, since he's a Dwarf fan, the Dwarf class came through the mashing process as a basically unkillable superman. The Dwarf kept all his big bonuses for the DC-oriented CnC, but then we use old-school flat saves. Thus, we have 7th level characters where the Dwarf has only a 5% chance of failing a magic save, but the Wizard has a 45% chance to do so. He refuses to hear any arguments about it though, because "its just simpler, like CnC" or "its traditional".
I'm surprised your group does not include a lot more dwarves. Consider hiring some henchdwaves, maybe? Seems like that's where this GM bias should lead. May as well focus on defensive bonuses, too. If that's the easiest path to success under the rules, may as well take it. GM bias creates the issue.