Yeah The Proteus is a pain in the ass to remove the lense but I found it to be the best for protection I was in a tourney last week I took 3 consecutive shots at 300fps and I couldn' feel it and my lens didn't crack( though anytime your shot at 300fps in the lens the lens should be replaced word of advice) and I would recommened using a N2 on the E-99 because I found it to work more consistently then CO2 don't get me wrong CO2 is perfect for the Xtra. But the gun I would HIGHLY RECOMMENED for a beginner is a Tippmann Custom 98 (my beloved first gun ) I added a response trigger to it and a Tear Drop 14" Barrel and it worked great my first year in tourney's(I'm in my Third year as a tourney baller)so I mostly know what I'm talking about.
Hope you get what you want!!!