Pay no attention to the naysayers, it's perfectly viable for 50 PvP. Yes, you have enough power to cause damage. 300k damage, 200k protection is not uncommon for me. Wearing a full set of Supercommando armor is pointless though, see #3 for the gear I use. PT tank damage is better than Jugg tanks, but still less than Assassin tanks.
No offense, but as AP I regularly switch to use ion cell when I see that would benefit the team. I have the exact same tools at protecting my allies as ST minus the accuracy debuff, and do roughly 10-20% more dps and significantly more burst and AOE even in ion cell compared to ST (at the cost of having more difficult to manage heat), meaning I can kill classes attacking my healer faster.
What advantages would you say ST brings over AP in that regard? For the way I see it it merely brings some additional personal survivability to the table, which is in most situations overshadowed by being able to do more damage.