I`ve got 2 Snugpak jackets one of whch I`ve hd 11 years & they use the same insulation in the sleeping bags as in the jackets. So I should think they are very good
I suffer from the same problem as you being rather tall so actually going to an outdoor shop & trying a bag would be a good idea as what I might think is ok might be no good for you at all.
The current army issue bags are very good IMO, loads of room if you get a long one but don`t pack down too small