Not much to add to the previous replies, except that I'd be very wary of the nosewheel RVs. They often have a lot of weight on the nosewheel and there have been many collapse incidents, often in the hands of very experienced and competent pilots.
The tailwheels save a bit on cost, weight, drag and maintenance and are very easy handling.
As for -9 or -7; the -7s are a little faster and sportier (cleared for aeros) whereas the -9s can lift more, land a bit shorter and slightly easier handling.
Personally, I prefer the tandem seat models.