There is no difference between the '07 boards and the '08 EXCEPT for the binding hole pattern
07' can only fit slingshot bindings and only has the four hole pattern.
08' slingshot added the standard hole pattern along with their four hole pattern to suit those who preferred to use other companies binding. However if you do use another companies binding it may sacrifice the flex a little because the base of the binding is wider on standard two-bolt bindings. (lots have been talking about using the CWB zeus for the '08 slingshots because the zeus base has been minimized for '08... But, me personally, i love slingshots bindings even though i have yet to try '08 gear)
If you DON'T plan to purchase new bindings too, DEFINITELY get the '08 so you can use your present bindings
ALSO, i think i have heard that the top sheet of the '08 board is a little different... i could be wrong though
AS for the bindings--- they added two new boots to the line. They have the D2 which is an upgraded version of the '07 drive binding. They added the PB Floid which is a more flexible version for those who like to grab and tweak more. They also have the Jewel- which looks like a PB floid for the women
As for suggestions of which board to get... i can only second what others have said, DEMO DEMO DEMO! I realize you said demoing is inconvenient because of location, but maybe you can try what i did--> drive to the nearest shop, (me, 45 min away) then rent a board and take it to the nearest lake and try to bum a ride from the locals. Don't forget to offer gas money)
Take into consideration that flex technology is a WHOLE NEW flavor... it may take a while to get used to (2-3 sets) so try not to judge it right off the first wake jump or cut.
I have never tried the Shane before so i cant give a just comparison, but i strongly doubt that I PERSONALLY will ever go back to a traditional board ever again. I am definitely converted to this new chapter of flex in wakeboarding history.