I'd play it differently:
FIN could add +1% to thievery monetary limit.
WIT could add +0.2% to bartering effectivity.
STR could add +1% to thievery weight limit.
MEM could add 0.1 or 0.2 (depends on how you see it) per point to loremaster.
INT could add 0.1 or 0.2 (again: depends on your POV) per point to persuasion.
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Why 0.1 vs. 0.2:
0.1 bonus for MEM and INT would be a pure addition, 0.2 bonus could be seen more or less as "replacement", because of the maths... I mean the "spillover" after you have issued the 5th civil ability point could be enhanced to be almost a level 5 civil ability for lone wolves.
0.1 (the addition) could help with not having to change gear so often on the other hand, which would be great too.
Didn't do the exact math right now (it's late here), but this is something I would really like to see. Can do it tomorrow for the level 18 "last real civil ability point" if you want (the one @ level 22 doesn't count if you ask me, because it isn't really that useful anymore).
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Ah, forget that tiredness... lets see...
+1 start
+1 at 2
+1 at 6
+1 at 10
+1 at 14
+1 at 18
= 6 (= 1 spillover for min / max builds)
+1 from "all skilled up" (I take this on virtually each of my characters)
+1 for racial possibly (at least bartering, loremaster, persuasion and sneaking are available this way - while loremaster isn't that great, having it @ 5 can improve the flow of the game somewhat)
= 8 (= 3 spillover)
+2 from my suggested 0.1 boost @ +20 = 10
Sounds right. Gives you two full final abilities @ level 18 if you want to.
And +0.05 would help out with the gear by giving you a full civil ability level @ 18.
(Yes, I adjusted it after calculation. Use 0.1 and 0.05 now for the values.)
Note to self: don't post while tired. ;-)
