CAUTION: the Surgeon General warns that reading this may cause drowsiness, blah blah...you know the rest.
The performance vs price thing is what accountants (shudder) call the
cost/benefit ratio. Costs can be quantified easily....benefits are a little harder....
BUT a little basic math (amount of cost divided by amount of benefit) tells you the closer you get to zero, the better off you are. I guess these days it is more of a "risk" ratio. Zero risk is great. For instance, if brake disk drilling costs $50 BUT allows you to NOT crash your bike just once, which would then cost, say, $500 to repair (not including whatever hospital bills for you), your C/B ratio would be 50/500 which equals 0.1. Not being an expert in this field I'd say a risk factor of 0.1 is pretty low. I'm sure if you looked on the net or talked to an accountant, you'd be bored to tears in no time with this stuff. Unfortunately that's the way insurance companies, car manufacturers and a whole bunch of other things work. There is even a whole "industry" doing this. It's called "risk analysis" and the big 5 accounting houses (Arthur Andersen, Price-Waterhouse, etc) as well as insurance companies and others employ literally tens of thousands of people doing nothing but risk analysis on a whole bunch of things. I'm sure someone somewhere sometime has figured out the risk ratio for, say, raking your lawn. LOLOLOL
Risk is one thing....stupid risk is another matter entirely. The trick is knowing where "the line" is, as in...."I'd better take this corner slow cuz I've never been through it before and who knows what 'surprises' wait for me out of view just around the bend??" We ALL do risk analysis on the fly everyday.
Superbike racers are in an eternal search to reduce the risk of the bike crashing or munching a piston or running into the guy ahead of them, etc etc. You can bet that those teams look for every "edge" to reduce risk and thus enhance their chances of winning by not breaking or falling off. They then work backwards and take "calculated risks" with their bike/equipment and their riding style to enable them to win. I could go on for hours with this stuff, as you know...but you get the general idea.
As to your question: the "benefits" of drilling brakes disks are SUPPOSED to be as follows:
less unsprung weight on the bike (every little bit less helps)
better cooling for the brake (gives higher, more consistent braking force)
keeps brake puck faces cleaner (again, higher, more consistent braking force)
easier to get rid of water quickly/dry brakes out faster (less "whoops" factor on initial application of brake in rainy conditions)
These "benefits" have to be offset against "cost" factors
cost of drilling
decrease in actual braking surface area available at any one instant
higher brake pad wear
loss of structural strength of brake disk
Can you/I actually figure this out ?? No....but it's already been done for us. The factories do it on their racers....so if you have a RACE bike, I'd say it's a pretty good idea. Don't forget, drilled disks were first used on racers, both cars and bikes, and that's good enough for me. Do you need it on a street bike ?? Probably not, for most riders....but it looks cool/racerish and that can't be all bad. LOLOLOL
Good luck with your drilling project and maybe you and Cappy can get together on this.