using a pipe bender for bending tube usually leads to very poor results - pipe and tube are dimensionally different and therefore so are the dies.
You can achieve acceptable results bending a decent grade pipe in a pipe bender.
90% of the wolf is built from pipe bent in a PA style 12-ton pipe bender.
But if I was to build a new chassis I would use HREW or DOM tube and spring for a tube bender.
FWIW - your fit-up, design geometry, notching, pre-weld prep, and welding will make more of a difference to the structural integrity than will the difference between pipe and tube.
But tube is nice to work with - smoother. Adrian likes it coz it's shiny too!