Just sayin, I'm not a big fan of the 3 bloodthirsters, its nice to have so much life steal and AD, but die only once and bawm, no AD no more =s, some attack speed would be nice, like uhm, black cleaver or pd's
another point, you have put points in the offense tree which seem a bit strange, for instance, you got improved ignite and the spell penetration, the AP gained from ignite doesnt realy help trynda at all, and the spell penetration neither since trynda does only physical dmg.
maybe you'd like to put suggestion runes like crit CHANCE in there, just for the early game rampage.
also you might want to try building averice blade > berserker greaves > B.F. sword > zeal > vampiric sceptre (> Inf Edge/Blood thirster/Phantom Dancers) the zeal, bf sword and vamp sceptre early game do miracles when put in the hands of a compotent tryndamere :D
I did like the part about the brush checking in there, I think alot of Trynda's don't know bout that :P
overal a nice guide, but imo could improve :P
thats all :P

because bloodthirsters stack..?

It's almost best but i prefer to get Phantom Dancer after Infinity Edge then The Bloodthirster

I Prefer to only get one avarice blade, then after the First B.F. Sword or Cloak I go for 2 Vamp scepters to help survivability. Still a +1 :)