Pardon my noobness, but when you refer to animation canceling, what exactly do you mean? Playing a Force Master and a Summoner so far, I didn't spot particularly blatant windows of opportunity to perform such actions, is it more of a melee thing? Granted I'm still low level, but for example playing FM, I spam alternating LMB and RMB on standard crap mobs, using F-fire or F-ice and reserve C-fire, X-Fire for harder mobs. Sometimes I fuck around with 4 to lift mobs to do a combo with V-fire, but it's hardly worth the hassle. I don't think I leave empty "globals" (inappropriate term, I know) in between.
Also, what's the deal with combos? For example in the tutorial missions, the ones where the little guy teaches you stuff, it suggests to do LMB, 4 and V-fire (Blazing Palm, lift the target and light a firewall). It doesn't add any special damage, it's just cool to lift a guy and light a fire under his ass, that I can see, but I didn't notice any particular boost in damage or other factors.