Having ridden both extensively I shall dive in with some knowledge. I rode the Absolute for 3 years and little has changed. I've been on the new Transcend since October. I rode each "finless" without extensions etc.
This board can be characterized as quick and poppy. The rails are extremely thin which let you set this board on edge with ease, its not the fastest board but can definitely get after it. The board has a huge vertical pop and lands pretty soft.
This board is similar to the Absolute but does things differently. The board is definitely faster on the water but not as quick rail to rail. The board has a big vertical pop but is more controlled than the Absolute, it also lands a lot softer.
Of the two I am definitely hooked on the Transcend, it does everything well. I really like how it releases off the water. Between the two coming from an 07 Marius I think you'd have an easier transition to the Transcend. I will say, folks that liked the 07 Marius such as yourself, really like the new shape Marius. A little easier rail to rail and from what I've heard, overall better in all ways. As always demo demo demo!