hi, psycho3, cryo2, wl here.
i agree with previous posts. i chose cryo2 for bigger better icewall and subzero shield.
my thoughts: i took cryo2 very late. icewall and shield are good but yes, you will lack a bit of dmg in the beginning while your cc is pretty good. ppl tend to seek for cryo3 or linker in parties but when they have me in a party i never hear anyone complain (well, if they do its because of the gravity-pole-crash or someone who does not like to be rescued by raise )
sometimes i wonder if wiz2 would have been a better choice, so i wont be interrupted in pvp. to be honest: if you play carefull you wont be interrupted much in pve. the PP stun is very good and you have many options to keep the mobs away from you. you dont really need surespell, only if you fight mobs that are way above you, since they might resist your cc, OR if you cuddle the furry blue archers.
i would not include linker to the build. i thought about it before obt, but right now it would just interrupt my rotation and the flow of cc.
runecaster always is an option, but be aware of the long casting time. i personally would not recommend to add RC to cryo c1. you would only use it for your IW+PP combo with a weaker and smaller icewall.
my suggestion is that you think about what c3 you theoretically would like to add to your build if you ever get the choice. maybe at one point you dont like the new classes. you could take the opportunity to build up your existing class c2 to c3.
tl;dr
if you get interrupted much ->wiz2
if you like mighty shield power and like to use your wall pew pew -> cryo2
no RuneCaster without CastFaster