Heh. Good luck. Worst case scenario, I bet you have plenty of random number generators rolling around. ;>
You're right that Able Learner is a very tricky feat. It seems to me that it has the main worrisome impact in the precise situation I've been looking at: it's not that swashbuckler and rogue don't have heavily overlapping class skills, because they do. (Or more specifically, rogue has every swashbuckler skill as a class skill, plus some 16 more.) So, it's really that rogues have only six skills (outside of the Knowledge skills) as cross-class. Bards are just barely lower on the totem pole, and nobody else even comes close.
The problem for me is that a rogue has a lot of class skills that *nobody* has--and those skills are one of the big class-defining features of being a rogue (so it feels like nobody should be able to get them that easily). On the other side, the swashbuckler (even though it promotes a high Int score and gives a pretty large number of skill points per level) doesn't really have a much variety at all. (My human with +3 Int modifier could max out all but two of the class skills at once, not counting Profession and Craft.)
So, I'm not sure quite how to handle things. I'm inclined to think that Cosmopolitan's approach is better, although perhaps changing it to two skills at a time would be more reasonable (and removing the strange "it must be a cross-class skill *right now*" requirement.) On the other hand, Able Learner does eat a feat, and it does require you to take at least one cross-class level into one of the highly-skilled classes.
So, if you're okay with making feat + one level of rogue making highly intelligent characters able to substitute for rogues in terms of skill use, it might not be such a bad thing.
(The thing that tears me, really, is that looking at the swashbuckler/rogue/Able Learner combo, I'm seeing the sort of intelligent urban fighter I've always been interested in playing... The urban ranger variant from UA still gets spells and a weird animal companion thing going on--and the bard has spell casting from the get-go, plus weird performance art things--and neither of those really fits the style of... well... a character like D'Artagnan, or any of the other (non-comic relief) characters from the Musketeers. So this combination strikes me as gorgeous, except... it leaves you wondering "What about the poor helpless rogues of the world? Don't they deserve some *love*?")
(Oh, and on top of that, I guess: the combo gives access to all of the skills I think such a character should have: sneaking around and spotting things, and a smattering of social skills, along with mobility. The swashbuckler class only provides the mobility, and none of the social graces. But the combination also provides access to the more arcane side of a rogue's skills--forgery, breaking and entering, pick-pocketing, which are less germane. So when I think about what I want to do, I end up waving my hand at half of the bloody skills on the list.)
Bah. Oh, well.

I must be up too late, this post just keeps getting longer. Good night.