My 25DS which was as a show model and I did recieve a great deal I could not refuse! I figured the warranty would take care of any problems caused by careless showgoers but have had not problems with drawers, cabinets, ect in the two years we have had it. I would not worry about buying a show model, as long as it hasn't suffered any cosmetic damage that would bother you. But if they aren't offering a deep discount, why not go new?
Don't worry about the furnace, that's what the warranty is for. Forest River does have a 2nd year warranty you may want to sign up for, but it is for major structural issues only.
We have grown quite fond of our 25DS. It is a lot of camper for the money, and considering the very light weight well built. It is perfect for two but roomy enough for 4 when our full size kids come along with the 125# mutt.
It looks like the only change the have made is to remove the TV shelf and wall mount the TV and stereo - a wise move on their part! It looks like they did not change the bathroom door yet - If someone is in the bathroom and you open the cabinet over the micro the door crashes into it and puts a nice gouge in the door!