Advice for an older rider

I joined the Snowmobile forum as in doing my research related to the purchase of a decent used sled, this forum seemed to have the most current information from a variety of members. My sled for the past few years has been a 1984 Skidoo Formula SS25 which I just sold as I was having great difficulty getting parts, and it was uncomfortable to ride for a 70 year old. i am now looking at two used Polaris sleds. The first is a 2003 Edge X700 121 track, 1.25 lugs with approx. 5000 kms (3200 miles) on it. The top end has been redone by a polaris mechanic. It has mechanicalreverse, hand and thumb warmers and is second owner. Looks to be in real good shape all around. the other sled is a 2004 Edge 600 Vertical Escape 136 track,2 inch lugs with approx 2500 kms. has electric start and mechanical reverse with warmers. I intend to do mostly trail, lake and field riding for deeper snow. Any advice on which sled would best suit and any reliability issues with either the 2003 700 motor or the 2004 600 motor would be appreciated. Also want a sled that is comfortable to ride. Thanks guys,

Advice for an older rider