I think that the 'has to be of equal enhancement bonus' clause certainly saves Sunder from being House Ruled (Allow the total weapon bonus to apply, so in the case at hand, +14 hardness and +70 hp). It's far too easy for a big strong giant to sunder your weapon, only in the majority of cases he won't be able to since he'll be using a mundane club.
Now, if a PC specialised in Sunder, at least you can circumvent the sunder rules by using more creatures with natural attack. Still, I'm not a big fan of how easy it is to sunder weapons - two-handed power attack is normally more than enough to take a blade out in one or two rounds which is far too easy.
Pinotage