It's hard to say, and the case depends on player by player.
Obviously, the bonus does have some value (free HP = free Survivability + Damage), so the question really is, does your off-spec gear have enough additional/better stats to outweigh the set bonus?
This of course depends on your off-spec gear, but also if you're raiding 10 or 25 and normal or HC (25 and/or HC should lead to more HP income), as well as your HP strategy. Do you press SotR the moment you hit 5 HP, or do you bank it until a HP generator comes off CD. In the latter case, you might lose out on some of the free HP, but arguably, that's when you don't really need it anyhow.
I thought Theck was sorting something out about it. For example, there was some gear tracked to see how much stats you would gain exactly by foregoing the 4 piece bonus. Haven't heard from it since.
See the comments in
http://www.sacredduty.net/2013/04/09/st ... up-longer/ for a little more info.
