I own a number of markers... probably too many, but I picked up a Clone GTi last year and was very impressed. Didn't have any issues with ball chops as mentioned above
It is more complex than some markers to maintain, but as long as you are comfortable with following instructions, it becomes second nature very quickly. Shot very well and was my preferred marker for 2013
HK KLR... I was planning to get some, but got tempted by the VIO as they were available sooner. Having now seen them, I think the VIO was the better choice. In fact I bought a 2nd pair of VIOs instead of picking up the KLRs. Great field of view, no fogging, lots of colour options, easy to switch lenses (once you have broken in the strap clips!)