It depends on what you play. Before I got chaotic stab, this stance was great. I only wish it had been in the game when I was doing most of my leveling, but no doubt it helped alot during the first couple hundred AAs before I felt like I could spare the AAs on chaotic stab. It makes duo-ing and soloing considerably more viable for a rogue.
I have found that while it does help a bit in soloing/duoing, it needs a little tweaking to be actually useful (it is often better to use /s 6 and /s 4 if you can handle it, or even /s 2 if you have a healer). Maybe I am just unlucky, but every time I use it I seem to get openings one right after another, before BS refreshes Though if anyone knows, Banjimen is probably the guy.
Its not perfect, but the slow rate of stamina use makes it nice (unless they've upped it since I've used it, it has been a while). It would be nice, though, if the openings weren't as spiky.
my main use is i duel box a cleric and rogue so hes tanking all the time inless we get a group even then at level 40 hes better geared to tank then most tanks at that level
in terms of how often the opening it appears it seems to directly focus off mob attack swings. when i solo minotaurs in lasanth it pops up frequently due to the extra attack rounds they are sending my way. There might be other factors that can create an opening too but mob attack rounds seem to be the big one.
It's quite a bit of work to keep aggro on a cleric with spells, heal, AND do your thing with the rogue. If the mobs aren't especially MR, the root & tank method works great.