Howztie mate,
Sorry for the late reply but I never saw your response until now!
On my first run through I played as the Infiltrator and thoroughly enjoyed it! Then when I started my second run on Insanity I carried over my Infiltrator but it was KAK hard, when you aim down your sites you don't even go into slow-mo and even the Loki mechs had armor! So I canned it it and started my Insanity run with the Soldier and cruised through the game

. Nothing can stand up to the power of the Revent Rifle!!
I want to try the Vanguard next, yourself are you planning on another runthrough before ME3?