I use a Motosportz damper on '06 610 and it makes a world of difference both in the rough stuff and at higher speeds.
Call Kelly at Motosportz, I don't think there is an issue using the IMS tank and Motosportz damper on the 610.
http://gprstabilizer.com/app_27_husqvarna_610 this also looks good but not a site supporter as far as I know