I don't think it's a legal list. Page 9 in the rules states that no more than 2 models in your team may have a 2+ save unless you buy the "Armored Might" theme for 10 points. You could go down to 4 Terminators and use the 30 points left to get an assault cannon or cyclone if you had your heart set on all 2+'s.I found that having a very small number of models in a team made it very vulnerable to shooting. Orks can take a withering number of big shootas, and while they don't hit much every armor save is a tiny coronary when you only have a handful of models on the table. Getting FNP helps a lot.
Something about Terminators "sneaking around" just doesn't sit well with me.Agree with Mike above too (beyond the rules) - one snake eyes and half your team is gone.
I don't knows about the "only 2 models with +2 save" The only restriction put is that no model may have +3 invul save.