Definitely buy a good mask before you jump in and buy a marker. Try on as many different ones as you can before deciding to purchase, that way you can get a mask that is comfortable for you.
I also shoot an Etek 4 and I love it! It takes maybe all of 3 minutes to take apart, clean and reassemble and has been bulletproof reliable since the day I bought it. I've also never had a break but then again, I don't shoot the most fragile paint being a scenario player
The only complaint I've really got is the sound profile as it can be quite loud but that's not such a huge issue and as for barrel sizing, I found that a couple of extra Shaft4 backs solved that issue for me. I'd definitely go for the Etek over the Etha