Hey there. I am somewhat new to eq2 boxing as well but I hope I can help.
I think it should work out pretty well. I run almost a mirror version of your team * SK, Mystic and Illy* and it has worked out very well for me. The defiler is great for the debuffs to disease and really compliment your SK. The thing I found was that while running them is that the mobs however never lived long enough the dots to do their work so I betrayed her to a Melee Mystic. I find that the damage she does really helps speed up single targets and her healing and wards more than enough to keep me up and going. I think it all comes down to personal preference to be honest. What I can say is you should have great results with either that you pick.

The healer is always a personal pref thing I feel. Alot will say Templar for buffs and heals. Others will say Fury for DPS, buffs, ports and regens. Some will say Shaman types for wards, buffs, debuffs etc. With an SK as your tank, anyone of them will fill the roll nicely.