I have both a Mana 82 and Mana 90. I am on semi flat water most of the time with some lake downwinds during the fall. On the Mana 82 I have a 100flex shaft and find that after 8-10 km my shoulders are done and often find I am sore that night right down into my tendons. On the mana 90 I am trying a xtuff shaft. I can do hours on that paddle and get tired but I do not have the same tendon soreness afterwards.
The xtuf shaft does flex a lot but I find that I always make the catch and feel the spring back at the end of e stroke. However it is the only way I can handle a 90 as I tried one on a 100 flex shaft for only 3k and I was sore for days. If you are over 150lbs I would suggest a xtuff stiff shaft instead.
As for speed I am able to go about .7 to .5 mph faster with the 90 and when I get tired it is nice to have the larger blade to land on as the 82 can be a little small when I get tired and occasionally fall in forward.
