It's an interesting concept in that it increases the pick upgrading prowess but not sure it's a good idea to add more sweetspot power to 35 rogue and less to 40 rogue (and everything inbetween) - seems like superbad compared to CL egos and way too onedimensional? Flat +2 or +3 to upgraded pick level would be better and still balanced imo, but even then not sure it'd be worth implementing. Basically a pure rogue would gain benefit of making +12s into +21s, non-pures would gain access to +24s (from 18s).
Riding on your thread a little bit on rogue ego ideas that could also be present on an ego: Crippling - increases chance of getting that multiplier to 100% and decreases level required for this benefit by 2 (so threat at 28 rog, multi at 33 rog). Oppourtunist - now also adds INT modifier to damage if it is greater than dex/str modifier. [would prefer this to be an universal feat but you miss every shot you don't take] Swift Crippler - Crippling attack now affects all targets in a small (tiny?) radius around your main target.
Baneknights would be balanced if they could splash paladin. -Caeha Everyone should stop using the same portrait so I can GR them better, damnit. -Caeha