without some damage absorption (Barrier), CC, or aggro management (a tank on your team), your only hope is to play very conservatively. This means relying on hit and runs, lots of hiding behind corners, and maybe Combat Roll spam. The video showcases this very well. Doing this makes Perilous manageable, but ultimately it's all time spent not killing things
Aggro management is not specific to tanks, but playing conservatively is true for all classes if you have none of the above in Perilous. If you have no CC, taunts, barrier or direct damage evasion, you must play sneaky and ambush the enemy.
Successful Ambush tactics are technically more downtime, but take less time overall because the time to kill required is much less. I challenge you to try timing a walking bomb line of sight pull vs a AW that charges in and spams spirit blade. The former kills everything in less than 10 seconds, the latter is still SB'ing the first target at 10 seconds.
I would have no complaints
I would, because it is amusing to do so, just about other specifics.
Point being, yes Katari is viable on Perilous
Aha, my gauntlet is thrown and answered to the Anti-Katari.
team composition notwithstanding
Team Composition always matter. You don't fight in a vacuum, unless you intend to solo. Also, better isn't always kill efficiency, but on the meta-level, 'fun' factor. Katari is 'fun' because there is variety and tension in the fight. If guard were as OP as fade shield, it would not be as fun (ok ok, it might). I have a reaver. It kills stuff fast with the right allies, and does terribly with the wrong ones. Ok, I lie, I still do fine, just not as nearly as well with terrible people in the group (I let uncooperative pugs die for good reason).
where a talented Katari player could truly outshine other classes
sacrifice output for ... survivability
I would actually do better with the Katari given his better mobility & survive-ability skills in clutch situations, than I would reaver, if I had terrible people in my group. Leading the enemy where you want them to be is producing results not sacrificing anything.
I assume you didn't look at the team results at the end. I had highest overall score, and highest kills. Didn't count how many times I rezzed others.
http://youtu.be/ubd037Eg7ew?t=15m20s
Here's the results at time 15 minutes 20s. Over 50 kills, 7.5k exp, beating out even the Ele, bronze kill streak. I've had higher (10+ ks's, 70+ kills, etc), I've had worse. High Risk High Reward though? Definitely.
Players unwilling to communicate & learn will never do well regardless of class, and yes some kits have a higher learning & gear curve than others... but the gauntlet is thrown. Katari is Perilous viable, and that cannot be denied as I've demonstrated it.