first of all to concider is, the height of the 660.
for me,the seat height is too high for getting on and off several times a day.
(i'm 1.78m)
mine was lowedered when i bought it 3 months ago, now tested as standard height... i'm going back to lowered setup.
the S10 might have a better step over?
the 660 is also a bit more vibey sice it's a single.
i think you will have to sacrifice some comfort if you go from the S10 to the 660.
try to rent a 660 or make a nice trip with a 660 befaore you pull the plug...
i'd love to have the S10!! can only dream about it...