You already mentioned migitation, where ice offers some great stuff:
Shiver: That thingy is cool when you sloooooooow the enemies down.....like freezing hell! And then go over to --->
Ice Patch: Some like it, some hate it....I think it would complement nicely with Irridiate.
When I look at hold an sleep....hm sleep ain´t so good I think because of the tickly stuff that rad offers. But the Hold seems nice then, especially when u are already standing in the mob using Irridiateand the say "Freeze!" That sounds nice 
I have a Rad/Ice at about 12, very fun and very versatile. I think it will work out quite well.
I'm a Mac user, no Mid's for me
I am interested in trying out a Blaster for the first time and think that Radiation is the one for me and my concept. I have looked on the boards to see what others are playing with Rad and it seems like /Fire and /Energy are the most common. I am curious what others think about Rad/Ice? /Ice looks to bring some heavy mitigation which seems cool.
Any comments or thoughts on Rad/Ice?
Thank you!
Got more funky styles than my laserjet got font