So the D2 Layer is a rather underwhelming in performance? I mean we haven't really got any tests yet but I'm having rather low hopes. The Dual Layer (layers) aren't really that impressive so far are they?
V2 does have decent attack but it depletes too quickly and it's not really that durable.
S2 is one I don't know much about but I've heard that it wasn't that good. I suppose it's because of the shorter teeth.
R2 bursts rather easily and has a lot of recoil.
K2 has decent defense but it does not have enough stamina to back it up so compared to Wyvern... eh.
D2 and W2 have yet to be tested but I've heard very negative things about the W2 Layer. I think the only one which may be alright overall is O2.
However, this is just an assumption and it might be my experience with the Layers.
Eh, I will think of something to put here...
... later ;)