Do you mean the Helly Hansen baselayers? If so, then I reckon just about anyone that ever got issued with the old style T-shirts probably has a HH. It is only recently that they have been issuing the quick-wicking type t-shirts, before them the t-shirts would just act like a sponge on a TAB.
I do admit that the new tees are good but find that a HH keeps me warmer when static in winter, definitely a good purchase (I always use one of my two green ones, one long and one short sleeve, because I think you look like a dork if you wear a Blue HH on Ex). Plus you can use them for civilian PT gear as well, rather than using issue ones and being a complete Tool.
As for compression shorts, I personally can't do it (Yes, I'll admit I've tried it). They do stop everything from rubbing etc, but they just compress a bit too much for my liking - if you understand what I mean. Actually the HH boxers are good, they hold everything in place without binding. But I suppose it is a matter of personal preference as to how much support everyone wants.