Almost all the archetypes are weaker than the original class, with a few that are decent. Even in the case of the few that are outright better, I would not be worried unless it was on an already powerful class. Even then it's not always worrisome. Menhir Savant Druid is blatantly superior to normal druid, but the bonuses aren't major enough to break anything. The only archetypes that concern me, iirc are:
- Teleportation Conjuror (APG, sort of like a "subschool" specialist): Conjuror Wizard is already crazy strong, this gets rid of the only not so great class feature he gets in return for 3 + Int per day
swift action Supernatural teleportation! It's like Abrupt Jaunt all over again!
- The gun mage wizard archetype (UC, forget exact name) - Overall it's an awful class for a Wizard 20, losing way too many good things for mediocre things, but it gets the ability to add the enhancement bonus of your gun to the save DC of your spells. NOT just your wizard spells. Making this a possibly too tempting dip for another caster. +5 save DC sounds pretty awesome to me!
- Ragechemist (UC) - Broken in the opposite direction. Read what it does carefully. This archetype is so laughably godawful, I'd ban it just to save a newbie player from thinking it's cool and horrifically gimping himself. On that same note, ban the Monk vows, especially vow of poverty. That is the most horrifically weak trap option I have ever seen. And it's especially unforgivable because any seasoned player can spot it for the horse dung it is in a split second. But for a new player wanting to play the traveling monk/martial artist that abstains from material possessions, they won't have any clue just how badly they've hurt themselves.
I think the Summoner class itself is seen as a little bit unbalanced (too powerful) by some of the community.
As for the archetypes, I think there are some that are clearly "bad", which makes the others good by comparison.
Summoner is as overpowered as you can get w/o 9th level spellcasting (*snicker*, they actually get 9th level spells, they just don't have to pay for greater metamagic rods to enhance them cause they come in 6th level slots). Which...puts it about on level with Sorcerer, maybe slightly better just for the action economy advantages.
Haven't seen all of them in play, but my general impression is that almost all of them-- except for the Monk archetypes-- are considerably and deliberately weaker than the standard classes.
Synthesist Summoner can be a serious problem, but I really think that whole class is a mess.
Most monk archetypes are weaker than the base class unintentionally.
The only outright better than Monk archetype is Qinggong Monk, since it lets you pick and choose what to swap so it's impossible (barring poor decisions) to ever be worse than baseline monk, only better or equal. But I did an analysis on QM and found it didn't actually add much of value, and the entire archetype was quite intentional to boost up the weakest class in the game, so it's not a problem at all.
Synthesist makes melee classes look pathetic since he can start off w/ all good stats high AC, multiple attacks, and pounce, and only get better from there. But he forfeits the action economy benefit of having a Summoner AND an Eidolon taking actions, so i think overall it's weaker in the long run. Maybe not right away when the Summoner lacks the spells and items to throw a spell every round.
On average the archtype is as strong or weaker then the standard class
There are exceptions but nothing that makes the archtype overpowered. They tend to allow the player to really fit an idea. ex. Druid vs Storm Druid (storm druid wins out in spell power where as regular druid tends to be better else where) or magus vs Staff Magus (staff magus AC can get ridiculous once past lvl 7, even when compared to regular magus)
I think not allowing gunslinger (and the various gun focus archtypes) is a fine idea, but then again I am not impressed by any of them and don't like the guns anyway
I hate the gun rules, they basically get to make tons of exceptions to the estabished rules all over the place and get away with it "cause they're guns!" I would suggest banning them if you use UC, along with the gunslinger class (or you could refit it to be a crossbow shooting class, I suppose).