the t series comes in a fixed draw up to 30 I think. so if you order it in 29, it stays at 29. very smooth cams on the t seriesSo you just need the longer release if you have a long draw?
the b series has a new riser and is fully adjustable. left to right, draw length, draw weight, all without mods. weight comes in 10lb groups 65-75 55-65 etc
the d series has a similar riser to the b but with i think a little toned down cams if i understood correctly. fully adjustable. left to right, draw length, draw weight without mods.
also all have adjustable brace height.
i have a t20 and a b34 and love them. fantastic shooting bows. have the b34 cranked up to 80 lbs, had it up to 86 but brought it back to 80 to get used to it. the t20 is great shooting and an awesome to pack and hunt bow. With the 29.5 in draw @ 70lbs with some light weight victory arrows im getting around 305fps. gets the job done on 30 and in on whitetail, pigs, yotes etc.