I may be wrong here...have only played Torchbearer once...but does he not have to max out the Fireball line to get a 1050, slowish casting fireball? Unclean Beast to me (I have played him in all but 1 custom game this weekend...and that was the only game my team lost) seems grossly overpowered compared to a DG whose sole purpose seems to be damage. At rank 3 of Venomous Spit, I am doing..what, 1050 or 1500 damage? I'm already matching or outdamaging the TB who should normally be a ranged-only DG.
I start the game with Swift Anklets and buy Boots of Speed right off the bat. Add in Venomous Spit, and I can harass the *hell* out of any other DG in the game. After that, I get the basic 5% +attack speed gloves...and start saving up for Heart of Life (4250 gold). Once I get HoL, it's all over. Yeah, I may still die....rarely..but for the most part I can fly around the map Spitting on DGs, retaking flags, annihilating creep waves, levelling and earning gold without worrying. Every 30 seconds, I can refill my HP and mana to full without going back to the crystal at base. Add in another set of gloves (Wyrmskin) and the Hauberk of Life and Vlemish Faceguard for +mana regen, and the UB becomes a fast-moving, hard-hitting ridiculous killing machine.
Torchbearer: A) Decent "sudden" damage at range with maxed out fireball, but it's slow to fire and does less damage than Spit when Spit is maxxed. 
Can't match UB's speed even with the same items due to Inner Beast.
Essentially, the TB does less damage at range (though he does it faster) and has to get into near-melee range to use things like Fire Nova or whatever the fire/ice Nova PBAoE spells are....which means, faced with Spit+Melee+Grasp...he's dead. The only thing that can save him is a good Sedna player healing him, or a QoT with Bramble Shield. But if they react too slow, and the Spit hits the UB...he''s gonna run. Guaranteed.
Overall I am thinking that UB's base melee damage needs to be lowered by about 10-15% to offset his ridiculous attack speed with items, and his Spit ability needs a good readjusting....on the order of about 20% when maxed, and maybe 10% less per rank before that. Alternately, TB needs a boost on his HP so he doesn't have to run every time he gets hit by a single Spit blast from a UB player.
Thoughts?