I don't think that splashing Blue adds anything that it doesn't take away by destabilizing the manabase and making it impossible to run Blood Moon. Maybe both Wheel and Jar deserve a slot if you're having trouble with not drawing enough. Oh, and I'm really liking Gigapede. Recurring untargetables that munch other guys in combat are great.
the number of colors in tnt has almost nothing to do with blood moon provided you can still run at least 2 forests. i ran 3 color tnt with md moons for quite some time and it wasn't an issue... with simulacrums i really don't see it being more of an issue now.
on adding blue, i was a huge fan of blue... and i definately miss ancestral, walk, and tinker. i definately think that draw in tnt is strong, but it's been my experience that casting draw spells is a critical loss in tempo... and tnt is definately a tempo deck. if i were playing blue i'd most likely add stifle as well because of it's tempo value.
however, the mana base does start to get shaky and right now one of tnt's strongest points is that it runs enough basic lands to not give a second thought to non-basic hate (especially b2b in hulk).
