I have run a T190, my BIGGEST complaint with operating is cold weather, no matter how much I cleaned at the end of the day. I was frozen in the morning. I feel that is with all track machines.
However, wheeled skid steers are great until mud gets involved. I have been stuck in mud or spinning a lot in it with only wheels. All wheeled skid steers need tracks over tires unless it is only driven on a hard surface.
Tracks: Steel are durable and protect the tires etc. Rubber tracks seem cool but I have not had any experiance with them.
I would take a long look at the Loegering VTS system, I know it is a lot of money, but that track system brings the track out like 8 inches farther forward than Bobcat tracks, increasing your tipping and stability. I have dumped a bucket load into a dump truck on uneven ground and had the machine tip and ended up facing the ground while still in the machine. Pretty scary. Anyway that is my 2 cents.
Think of it this way, add $7.00 to your hourly rate for 1 year at 40 hours a week and you'll make up the 15K.