StreamOfTheSky said:
Related question: I saw in the General forum E6 thread that we're supposed to just discuss it there, and not propose new feats/rules. So, is there anywhere in houserules to do this? In particular, it'd be nice to make higher level ability feats for classes not yet covered. I am kind of shocked there was nothing for a 6th level rogue to gain Improved Uncanny Dodge...
*shrug* Well, you could do it in this thread, or spin off your own.
Keep in mind that part of the whole point of E6 is to restrict stuff. Ryan explicitly didn't want to deal with the "more" aspect of D&D. More HP, more special attacks, higher BaB, higher saves, and so forth. In general, the point of most of the fans of E6 is to restrict power overall. The "low magic" and "grim-n-gritty" types tend to like low level D&D play.
In your particular case, the easy solution is to simply run the game as an E8 game instead of E6.
With that particular feat though, depending on how it was set up, it'd basically be a no-brainer for a Rogue to take. They'd _never_ be Sneak Attacked, since it'd never be possible to actually _be_ 4 levels higher than another Rogue.
Which is possibly another reason why folks haven't played around too much with it. Another aspect of E6 was to maintain maximum compatibility with D&D. At its base E6 (as Ryan made it) is basically "nobody and nothing levels over 6th level" period. After that is a series of additional things that people can use, but you don't _really_ have to do anything more than that for E6. Once you start having things like Improved Uncanny Dodge, well some folks are going to say "that's over-powered since it can never be negated" and then a new rule is made to try and deal with that, and it just keeps going from there.
It's _much_ easier to sell people on the idea of "nobody levels after 6th level, you just get to take feats" than "I've got a whole bunch of houserules I want to play. The first is that nobody can level past 6. After that you can take some extra feats, but they're not the same. Instead..." Too many houserules are a turn off for many people, even those folks that like to houserule games in the first place.
Like me for example. I'm running an E8 game. And I haven't used a single one of the special feats that everyone's made up. And I don't plan on it. I personally find it over complicates an elegant approach. At some future point I might change my mind, but right now I don't see a point. To be honest, with the number of books WotC has put out not including 3rd party books? There's no shortage of feats. Sure, some of 'em are geared for high level characters, but then those feats basically boil down to powerups because everything else has been powered up and can therefore be ignored.
And if none of the above applies to you or means anything to you

...
Well, I'd be tempted to simply change the requirement to be 6 levels of Rogue and 2 additional Rogue Only feats. At that point you're basically done. Anyone that's got the feat can never be Sneak Attacked.
If you _still_ want to be able to Sneak Attack a character even if they've already got Improved Uncanny Dodge, the first thing I'd ask is "why?" Seriously. All you've done is given them an ability that can be rendered useless. Which is about the same as having never given them the ability in the first place. If you still want to do that though, then I'd just change it to be "unless the attacker has at least four more Rogue Only feats than the target does."
I like simple solutions, so the above may not work for everyone.