Other:
The CAT one has a air tank which you can replace, but the connection between the air tank and the frame is really janky. I guess it works but I don't know how much a vibration issue it is and if the tank can loosen. I don't think I would manufacture something for sale which such a mechanical interface:
On the lower left corner:
https://images-na.ssl-images-amazon.com/images/I/71Q0sTqsfPL._SL1354_.jpghttps://images-na.ssl-images-amazon.com/images/I/712UlpiLmQL._SL1314_.jpgIt looks like some mad max shit, with the bracket bent into shake so it kind mates with the tube... I think proper manufacturing would be to weld a small plate with some holes in it to the square tube
On the lower right:
https://images-na.ssl-images-amazon.com/images/I/718N2LpKVKL._SL1190_.jpgYou can see that the tank is only mounted to the tubing stock by 2 points of crappy contact, that is a bolt and a nut. A bolt is not supposed to act as an anti rotation feature in general, and its definatly not supposed to act as a anti rotation feature on a round tube. If they want to use a detachable compressor it should be on 4 points of contact with parallel carefully welded plates, not 2 points of contact using bolt/shitty bent plate interfaces. Also does not appear to use any kind of anti rotation feature like lug nuts etc.
What can happen here I think is that the tank can loosen and increase noise, and possibly damage the welded connections by stress fatigue, especially the copper tube.
Final Opinion: Pay the extra 50 bucks for the well engineered product, considering its high pressure air. If this is the level of thought they put into designing it, they might also have shitty QC etc.
Since you bought it already, I would recommend that you either (not sure whats the best option)
1) weld the tank to the frame (kinda stupid?)
2) replace the nuts with some kind of anti rotation nuts (the ones with the plastic that deforms, forget what their called, or lock wire)
3) put loctite on it (the green kind thats supposed to flow into the bolt/nut interface would be easiest because you don't need to dismantle anything).
4) mod the thing to have a nice removable tank connector thing like I described, but its alot of work and i Don't know how easy or wise it is to weld something to an aluminum tank.
5) cancel the order and buy the rol air one for 50$ more