Hello,
Having been a trucker and owned 4 of my own semi trucks I can tell you that start up and shut down is no longer an issue with modern diesels and it is now encourraged because excessive idling is harder on them than starting a shutting them down properly. So that myth is busted. Just let it warm up for a few minutes before operating it and if it has a turbo let it idle for a few minutes to let the turbo slow down and cool off while it still has lubrication which isn't a problem with a non turbo diesel engine like most of these Sub CUTS, CUTs andGarden Tractors have.
I own a 1989 JD 430 diesel that I paid $800 for and it runs like new with almost 1900 hours on it and uses less than 1 gallon of fuel for every 2 hrs of use cutting my 2 acres. I never have to run at more than 1/2 to 2/3 throttle because the 20 HP diesel has 37 Ft Lbs of torque which is what really matters. This is about double the torque of an average 20 hp gas engine which is what makes these diesels feel so strong.
I would seriously consider the 2210 or 2305 which really isn't much bigger than the 595 and is actually about $2000 cheaper if you eventually have to add a 3 pt Hitch or 540 PTO to the 595. Also the resale will be higher a few years down the road on the SubCUT.
You could remove and store the 3 pt hitch on the 2210 or 2305 if parking space is tight and then just put them back on when its time to sell if you don't need them.