I'm not real crazy about the Toro entry level Timecutter SS series ZTR's(which is what you find in the big box stores), but several users here have purchased the Timecutter MX5060 ZTR and are quite pleased with them. Of course, that 50" ZTR is about $1K($4199) more than the one you are looking at(they do have a MX4260 for approx. $600 more than the SS4260 you are looking at, but the MX5060 has a much beefier deck than the 42" with better anti-scalp rollers). It's really hard to get into a really well-built Residential ZTR for less than $4K-$5K, but of course it's your money not mine:0) I'm just giving you my opinion on what I would do.
P.S.
The MX5060 "does" have the ZT-2800 serviceable trannies too!!!