I disagree with this completely, the whole point of the catch is that it is the /one/ thing which stops a supernatural being from being super tough or heal really fast.
Right. The one thing, not counting other stuff that counts as satisfying a Catch. For example, a WCV doesn't have a Catch with respect to Swords of the Cross ... yet Swords clearly count as Catch-satisfying nevertheless.
A fast healer will /always/ heal fast so long as the catch is not involved every time
I've put in bold the key part of this statement that makes it a non-argument.
Plus it is listed as one of the ways to generate power in the Living With Magic section in YS indicating its a perfectly valid method.
Please note that I am in no way suggesting that anyone should remove the ability of casters to power their spells via sacrifice. Just that it makes sense that the sacrifice should be a sacrifice.
and their is nothing in canon to support such a house ruling or else it would likely have been included in the books.
While I think the DFRPG books are amazing, I stop short of claiming they are perfect in every detail.
Once you start house ruling it becomes a slippery slope, which is not a problem in and of itself, but its easy to take it too far and I'd say this is one of those cases imo.
As it stands, a rules-abusing player could spend 1 refresh to allow them to gain +19 toward their complexity requirement to Thaumaturgy per scene skipped. How? Simply buy Mythic Recovery [-6] along with The Catch:
Only Works On Knife Wounds [+5]. Now each scene you skip, you can get the usual +1, plus you can inflict and immediately recovery from three mild consequences (+6), plus you can inflict a mild, moderate, and severe consequence which you will recover from before the next scene (+12).
If he had a partner with the same ability, that would go up to +37 per scene, and at a -1 refresh cost, why not have the entire group take it? Five players each taking this would make it, what, +91 per scene? Not only that, but they'd never have to worry about knife-wielding thugs again...
Combine this with a sponsored magic power that grants Thaum at the speed of Evocation, that translates to being able to cast death spells against people in combat simply by stabbing yourself while chanting. Sure you need to make sure that you don't take another consequence before the end of the scene, but that's doable.
Frankly, I think I feel safer with the risk of maybe going too far down the slippery slope, thank you.
As always, this is my opinion. I don't enforce rules for other people's games.