Icebreaker 320 as an layer?

I have both a 320 hoodie and zip. Depending on conditions I just wear one (leave the other at home) and not use a base layer. Icebreaker is very warm for me. Standing in camp I will put on my Patagonia micropuff over the Icebreaker and am nice and warm. Temps 25-30. It's a pretty warm piece of garment. If she runs cold, as I do, she may want a base layer under that in the colder temps. I always use a windshirt with temps 40 and above over the 320. The hoodie is good for sleeping. It is heavy, but well worth it.

Last October on AT in N. GA I used the Icebreaker 320 over a Patagonia Capilene 1 T shirt around camp in p.m.and early a.m. with rain jacket over the 320 at temps from 35-45. I was very comfortable.. I recently used the 320 as a baselayer with the Cocoon pullover in the high 20s, was very comfortable..

Thanks for the replies.
It looks like it will do the job well.

how heavy are these thick base layers? If someone doesn't mind could they weigh one of the 300+ base layers for me and tell me whether its a M/F S/M/L. I have the 200 and 150 bottoms and tops and they took me down to 15F with a thermawrap jacket while i was hiking in nylon pants. I supplemented with gloves/blaclava, and when in camp used my quilt as a jacket. THe 200s were what i used most of the time.