Well, for me, I made a break-out cable that is basically I think 8-gauge cable. The set of wires is not in the common jacket and I use that to test under a load. I use one of those clamp-on ammeters to measure.
Also, try to route your lights into a single source of power or at least per circuit, so you can test what your load is.
Trust me, I work 20 hour days, 7 days a week, 365 days a year, and on top of that... no, i'm not going to bore you with details.
You're running a business, act like it. Save your boxes. I think you got some power issues, and it sure as heck can't hurt to have some surge protection on those lighting circuits. I get stuff done. I don't work in an excuse-oriented environment.
Whether you keep your fixtures or change them is your issue. You can upgrade to Martins and and have more expensive fixtures toasted. Test your power. Get a whole-building surge protector and ensure you have a nice stiff power supply. Personally, I find the power in most clubs sucks worse than a blackhole. I don't expect yours to be any different. I take measures to ensure I can get the best I can from what's there since I know the club owner won't spend a cent on electrical, much less an electrician. Honestly, I don't care, I just isolate from their power as much as possible and protect my gear.
One club I went to has had the same bank of circuits at 95 volts for 15 years. He won't fix it. I won't work there. Got tired of his choice of every suck band in a 300 mile radius calling his club home. Yeah, maybe some day one guy will take a music lesson.