I've always been around my brother's and their rigs. They all run ARB's the rover is locked up front and rear... He has never had a problem with his air compressor, but it just is too small to pump up his 35's. He can't run air tools off of it. Or do anything with it except use it for lockers, which of course it was intended. So I'm not griping at that.
But then my brother Scott with his 84 CJ (which is now a mix of years CYJ-7) only had a rear ARB (which is now mine). I didn't take his pump because he forgot to take it off the frame before he gave away the old frame and body, but also it was in need of a rebuild or something, because it would every now and then work for the locker... He'd be in moab, hit his switch and it would "sometimes" work. He tried contacting ARB, but they gave him the runaround telling him it was either his air lines or the bulkhead fitting. He upgraded to the heavier duty stainless steel air lines, had the bulkhead fitting replaced, the copper wire inside replaced. He was always running into problems... Again ARB gave him the runaround And again, never able to do anything extra with the compressor, which is alright because it was not "intended" to do that.
Now my bro has "given" me a york compressor and he said for about the same price as an ARB compressor, I can get on-board air running with a 6 gallon resevoir above my dana 44 and have the ARB feed from that, and I can run air tools on the trail... And still keep my stock air conditioning.... That's why I look above and beyond the ARB compressor.
Sorry for the length... Just my opinions.