Well, I figure that the pursuit avenger shines better vs. certain kind of enemies. Lurkers, skirmishers, and artillery type monsters are what they should focus on, in my opinion, since those monsters either don't want to be in melee or want to move around. If you keep the artillery in melee or keep skirmishers and lurkers from moving around you're already putting a serious cramp in their tactics, even if it means you're not doing fantastic damage.
I think you're probably right that avengers often don't get high damage numbers (remember that retributive avengers have to take a beating to get bonus damage, unless they get lucky with resistances or somesuch), but I don't think that they
should have as high damage as other strikers - they already have about 20-30% higher hit chance. Having the same numbers for damage would be terribly unbalanced, in my opinion. I think avengers are supposed to have lower average damage, but be more consistent in landing it. But of course as a pursuing avenger your bonus damage really does depend on how DMs play monsters and which monsters you pick as your oath target. I mean, if you have your choice, a pursuing avenger probably shouldn't oath a brute or soldier or melee controller

(Do as I say and not as I do - I realize I just went straight for the one soldier on the field in the Dextyr game, haha.) And that leads me to my next point.
I think that DMs should keep in mind that the monsters don't know that attacking/moving affects the avenger's censure, since it's not an effect applied to the monster. 4e is of the philosophy that a creature under an effect knows exactly what that entails mechanics-wise, but the censure effect is one that applies to the avenger, not the monster. After they see it a couple times, fine, but until then avoiding triggering your censure is like avoiding clumping to counter a wizard.
Lastly, part of why I like the pursuing avenger is the mobility, especially as an elf. I mean, I moved 11 squares, including a lot of difficult terrain, and made two attacks in the same round. The only way something is going to get away from Tristan is if it's flying or swimming under water

That mobility also helps them get to those targets I mentioned that I think should be their prime focus, since they tend to hang out on the back lines.
In any case, I won't change Tristan unless I get really disillusioned with the pursuing avenger (which I don't see happening, to be honest). I don't mind playing a sub-optimal build, and I don't think Tristan is really all that sub-optimal.