My real world experience has been in HVAC, but I’ve read “Refrigeration for HVAC techs” a couple of…

My real world experience has been in HVAC, but I’ve read “Refrigeration for HVAC techs” a couple of times and watched an abundance of Nor-Cal Dave and Chris from HVACR Videos :) I got lucky and had an acquaintance with a small business working on beer draft lines, and I’m now (past month) running anything refrigeration related that comes to that company. So I’ve been able to repair a handful of walk-ins, a few reach-ins, and some glycol chillers for draft lines and fermentation tanks. I want to get better at posting my questions since I’ve learned a lot by reading techs’ answers on other forums. A couple questions from today…New restaurant is preparing to open in a few weeks, they took over a space and wanted me to start up the walk-ins to check for proper operation. Self-contained Norlake cooler unit and a self-contained Norlake freezer unit. Both running R449a. Freezer unit was completely flat. Pending approval, I’ll head back to find the leak. Just wondering, is there any reason for me to not switch to R448a after the repair is complete? This is just because I have a jug of 448a already and I thought I read somewhere that it was a superior refrigerant in many situations. The cooler was also not operational. Compressor kicked on, sounded rough, checked the start winding and it was pulling higher amps than it should, so it looks like the potential relay was staying closed. Cooked the start cap, so I learned my lesson to shut the system down more quickly next time. I was wondering why I shouldn’t stock various sizes of Supco’s start cap/relay combos. I can get the OEM components, but if the Supco part has an actual potential relay and start cap rated for the same range as the OEM, is it really a problem to install that as a permanent solution?