You know I've never actually seen Lenny even though I've played on that server quite a bit. Am I missing out? From what you're saying he sounds like quite a character.
Lenny is a decent berserker, but that's not really hard to do. Other than that, i don't think I've seen him play any single perk well.
Best story I can give with Lenny, joined a friend (who runs with Lenny frequently) on their server, and Lenny just happened to be on it. They were zerk kiting wyre on Suicidal, I joined mid wave 6 so I get to start on the FP waves. I get my axe/katana/LAR, and start to play the game. Everything goes smoothly through wave 7, as we double and triple teamed the FPs that came during the wave. Next wave is wave 8, 2 of the zerks die within the first 30 seconds to a minute, so it's now down to Lenny, another zerk, my friend (a medic) and myself. First FP of the wave one zerk and the medic go off doing their thing with the FP, so that leaves me and Lenny to the rest. He takes on some scrakes and I end up taking the FP that comes right about this time. I successfully kite the FP and kill it, then proceed to slow pick off sirens and husks. Well Lenny gets a group of 3 scrakes to kill, while I take another FP that spawns. I get the FP killed but I'm down to around 50 HP, and I hear Lenny on mic saying "Someone get me a heal, I need healed" so I run over to where he is, he's only down about 40 health, and I pop a heal in him figuring he'll heal me too. Nope, he doesn't help heal me, he decides to self heal and run off. So I'm thinking to myself "screw this" and go off to fight some more. Not even 30 seconds later Lenny gets raped by a triple siren and a husk, and he starts saying on mic "where the hell were you kamikaze, you don't know how to play, you left me get killed." I was like "You self healed when I came from 1/2 way across the map to help you out and heal a whopping 40 damage while you still have 3/4 armor, and you don't even bother trying to heal me who was at half health and no armor." And he's like "whatever well you're gone, you are garbage at this game and don't know how to play teamwork." Lets just say I left before he could ban me.
That's my biggest run in with Lenny. Any time I've seen him or heard anything about him he sounds like an idiotic douchebag who can do nothing other than Kite.