I remember a while ago that someone showed the math that reducing the penalty meant it was an appropriate thing to use more often, and the feat ended up contributing more total damage. This was with the 1:2 ratio of damage. But I'd be concerned about reducing the penalty - that actually made it stronger.
It was several years ago so I can't vouch for the math, but if correct than the effects are counter-intuitive. For example, if your options are +0/+0 (normal) and -2/+4, then the -2/+4 will be the mathematically correct move enough more often that the total damage added over hits will be more then if your option was -5/+10.
-5/+10 is more of a concern when you build around it and get either buffs from your party (bless, etc), or buffs from your DM (higher ability scores, regular +X magic items, etc.).