Higher priced battery packs have better quality control, so you're very unlikely to get a lemon. You might get a low cost battery pack that's just as good as one that's more expensive, but the likelihood is lower. Also no one talks about lifecycle. Now maybe to the serious racers this isn't an issue because they are throwing their batteries away every 3-6 month because the IR has gotten over 1 milliohm. But I've seen the cheaper lipos I purchased when I started becoming unusable after a year or two, but all brands. One of my cheap ones was holding it's own against higher priced ones. But I also have a high priced one that's still one of the best ones I have after several years of use.

Haven't seen any tests that look at number of cycles before a unacceptable threshold is met.

Most of us have somewhat of a budget for this hobby/profession and aren't fully sponsored drivers. Buy/run whatever is in your budget. Spending $50 more on a battery, might not provide as much improvement as taking that same $50 and buying something like a better motor, servo, tires, etc.

Also with a brand name, you're paying for a marketing budget, sponsored drivers, etc. There's a lot of overhead to run an RC brand, especially one that's race focused.