Just bought one of these after 6 years of the sv.
I was not finding the sv comfortable enough in my old age on longer journeys. Scoured ebay, auto trader, loot etc for several weeks, keeping an eye on prices. Eventually sold my sv for £1900 and the next day bought a 2000 (X plate) TDM 850 in silver, FSH, touring Scottoiler, 2 into 1 CCC can,taller screen, new c+s etc etc for £2,050. There are some bargains to be had out there.
For the 1st couple of days I wasn't sure I'd made the right decision, felt a bit gutless in 4th and 5th, fuel economy wasn't as good as the sv. Now I love it. Much more comfortable, can throw it around like the sv, goes like stink when using the right gears, costs around £40 a year more to insure and fuel consumption isn't actually that much down on the sv after all. Around 130mph top end.
For me it was a good move. An hour's test ride will not necessarily tell you whether you'll like it or not, you really need to use one for a couple of days.
Have a look here
http://www.carpe-tdm.net/tdmforum/
There was a major update in 1999 so a 1999 onward model is your best bet. Changed to 900cc in 2003.Apparently the brakes can bind if not used/looked after regularly. There's NO storage space under the seat.
HTH