Depends on a few things.
I'm not that familiar with Woods products, other than they are well regarded and of high quality.
You don't give us much info on your tractor - Is it a gear drive, or hydrostatic?
A 60" cutter will probably work fine either way, but it depends upon what you're cutting. If you are doing heavy cutting (saplings, bushes, etc.), you may wish for a smaller cutter, or a bigger tractor. If it's mostly pasture and weeds, your tractor (assuming it's 29hp) should do just fine with a 5-footer.
The dealer most likely is pushing the one on the lot vs. what may need to be ordered.
I used a King-Cutter cheapo for 5 yrs, but a Woods is a Cadillac in comparison . The KK worked just fine though...
Lunk