I own several now. One has a slow leak, another dumped all air and needs poppet replacement now (widely known issue). Not many problems with Challenger Pro, I think it's one of the best AEA released so far. HP Max work file too. Have lost of cycling issues with .22 SS though, trying to fix it by polishing internal parts and modifying mags. Also, I will have 30 cal Carbine in my hands soon too to try, I heard larger cal semi-auto AEA cycle better, will verify. What else... Ah, SF 22 is actually pretty good, and I love that you can switch between semi and single, unique feature. In general, I think that they are worth the price if you are ready to put your time and effort into them to fix various things. Once you get it running smoothly, it's a great platform!