if you are talking about a speed twink, then sockets > all, so yes you should use them. For WPvP, you'd have to test it out really - is the gain of 2 (or 4) sockets better than losing almost 50ilvls on your main weapon. Stamina imo is not something you should worry about - an extra 2-3k hp won't make a big difference. If the extra secondary stats offset the loss in mainstat + lower base secondaries, then yes.
For example, on my resto druid twink, 1 versatility is about equal to 0.9 intellect when it comes to increasing damage - so if I had the heirloom I'd probably use it. Not sure if other classes use versa as best stat though, so I can't speak for them.
If I had to guess, in general I would say a dual-wield class that gains 4 sockets should probably use them, while a non-DW class shouldn't.
You should be adding a 120 and 80 main stat gems to your gear anyways if you're WPvPing, so it's not a factor here.