If you have any interest in playing against other people, you'll probably have to get Diplomacy.  (Most of the PvP players who owned Entrenchment bought Diplomacy, which is where most of the PvP action is now.)  There are still people playing regular Sins and Entrenchment, and most of those games are in fact comp stomps, but they're mostly groups of friends playing private comp stomps.

Entrenchment was a good addition to the online game.  Diplomacy not so much, but just about everyone who played Entrenchment bought Diplomacy and that's where we are now.  You can probably still find comp stomps for regular Sins and Entrenchment though you will probably have to be patient and ask groups nicely if they'll let you join them.