I've both Titan and Valken 3,000 mAh 11.1v Li-Io's, Deans connector, used in rifles either with GATE Titan's v2's or Double Eagle's knock off of a Titan, and so far I can overall fault neither and I'm very happy with them (used Li-Po's all the time before I made the change, and the last time I had any NiMH's was back when I raced RC cars). I'd say though that the Titan's has a better overall build quality, the cabling thicker and more flexible, plus the casing / heat-shrink is better applied (with Valken's looking a little rough around the edges).
It was mine and my son's Double Eagle M900's that pushed me to Li-Io's, in that the controllers in them will let a batteries cells get down to almost 3.2v per cell before the battery protection kicks in which is far to low, and this caused one 1,450 Li-Po to get too low at one game and it puffed ever so slightly and has not been the same since (it's in my emergency battery pile now).
The Li-Io's can safely handle going down to a much lower cell voltage, 3.0v or a little lower, with zero negative effects, who know if this is down to their construction or the 18650 cells they use (different from the flat Li-Po cells and how their conductors are layered?). I've accidentally left a Li-Io in a rifle for close to a week, I totally forgot about it which is not like me at all, and it went to under 3.0v per cell, but charged back perfectly (but took a while) and has shown no negative effects at all.