Shay comments that the Evo got a bit soften this year. Angry Snowboarder said the SL and Evo are the same this year with just graphic changes (don't quote me on this, i think i remember seeing it somewhere).
Apparently the flex discrepancy between last year's Evo and this year's Evo-R was due to a typo in the NS catalog, both boards do in fact have the same flex level.
They're so close to being the same board this is the difference. SL is a directional twin, Evo is a true twin. I've owned both and ridden them all over and either or would suit what you're describing.
So I got curious and emailed NS. Here's what Vince from NS said:
Thanks for contacting us and your interest in our Evo. The confusion on
last years Evo is our fault. There was a misprint in last years catalog
showing the flex of the Evo as being stiffer than it actually was. The
board is comparable to last years boards in regard to flex. This year we
have our pressflex core. We profile the core so that there are 2 softer
flex points between the bindings. Allowing the rider to manipulate the
board for more torisional control. For foot steering, pressing, buttering
and overall freestyle control.
Does this mean the board is the same as last years, or softer?