Cephid said:
Like snap kick an extra attack for 1 feat. Can even be used as part of a charge or standard action. That is just silly.
And one feat that lets a monk count as 4 levels higher for unarmed dammage. With a monks belt, that means a 12th level monk is doing 2d10 per hit going up to 3d8, 4d8, 6d8, 9d8 with size.
Snap kick is an off-hand unarmed strike, with a penalty to hit. Unless you're a mid or high level Monk, it won't do much good. You need to use a melee weapon attack first. You get a -2 penalty on attacks similarly to a low-level monk using flurry of blows. Again: it's not much good unless you're a monk, and even then it's limited. Half Str bonus to damage with the kick, and -2 to hit with all attacks that round, and the Monk's already-mediocre attack bonus and Multiple Ability Dependency.....
Joe Fighter 6 does 1d3+2 nonlethal damage in exchange for -2 on all attack rolls for the round....woop dee doo. Joe Monk 9 does 1d10+1 normal damage in exchange for the same attack penalty, and is lucky if he even hits at all....woop dee doo. The feat requires +6 BAB and Improved Unarmed Strike, so that's the earliest either guy could take it. Think of it as a sort of alternative to TWF. It could be used with TWF, of course, but then you'd have an even worse chance of hitting anything at all (and if you're a monk, you're better off not even trying to use both at once).
I really, really don't think Snap Kick is any problem.
Superior Unarmed Strike is a good feat. It allows non-Monks to suck less at grappling and unarmed combat when they get disarmed. And for Monks, it boosts their piddly damage.
At 6th-level (the earliest they're likely to get it, with its prereqs) the Monk will be dealing 1d10 damage instead of 1d8, so a bastard-sword-equivalent instead of a longsword-equivalent. At 8th-11th level it'd boost their unarmed damage to equal a greatsword, but it's
only an average increase of +1 damage from where it would normally be. Later it improves to 2d8 a bit sooner than normal, and then later it improves to 2d10 (that's as high as Monk damage goes).
So eventually it is worth +2 damage on average. Kind of the Monkish equivalent of weapon specialization but not quite. The Monk doesn't get weapon enhancements for his unarmed strikes. He doesn't get +5 or flaming burst or other stuff to boost his damage and accuracy; the Monk doesn't really get access to anything for greater accuracy or damage, except for Weapon Focus' piddly +1 to-hit and, in ToB, Superior Unarmed Strike's 1 or 2 points of extra damage on average.
I don't know where you get those higher damage values, since a Monk's Belt also won't exceed the normal limit of a 20th-level Monk's damage (2d10 if Medium, etc.). If you're playing a Large or bigger race, then you've already got a level adjustment and/or several racial hit dice holding you back.
If someone casts Enlarge Person on you, well, that's easy enough for an enemy to dispel, and it's really not a problem with the monk (an Enlarged fighter does 3d6 with a greatsword, and an Enlarged goliath can do 4d6 with a greatsword, and a half-giant psychic warrior can Expansion themselves up to Huge to do 6d6 with a greatsword....). It's really a problem with Enlarge Person/Expansion in 3.5E more than anything else.
The Monk's Belt might be something of a problem, but I dunno. It's certainly not hard to destroy if the DM really felt it was causing a problem with the character (Disintegrate anyone?).