I appreciate the confidence. I think that a ROC of 1,700 to 2,000 pounds is a nice sized machine for your application. Your weight restriction of 6K is tough to met. However going to 7K allows for more options. What I like about this size machine is the 12X16.5 tires, good power and still keep the ability to keep the machine narrow. The CASE machine can go to 66" in width. That is very important I think in lawn prep. I would try to stay with a radial lift as your visiblity is better. Since lawn prep requires going backward more than going forward a lot of times that is also important.
I would try the following machines
CASE 430 It has a 2000 ROC and a net of 74 hp very good breakout force. I really, really like the control system on these 400 series machines. This would allow for enough capacity to move topsoil with good production rates and will handle oversized snow buckets. Also impressive is the aux. flow of 21 gpm one of the highest in its class. This will make for performance running rock hound type attachments.
Bobcat 205 This is a vertical lift machine. I like this size of machine my only issues with it is its dismal performance specs. 16 gpm at the aux. hyd. The breakout is only 3800 pounds and its hp is around 61. If you don't mind going over 7K the Bobcat 220 is a better specing machine but is larger. I demoed a 220 and I liked it.
CAT 246B This machine specs very close to the CASE 430-440. Actually there is almost no difference between the two spec wise.
If you go to this web site they have an excellent web site to compare skid steers. Pick a couple of machines and met the salesman and decide who will be there when you need them. Then the fun part, start setting up the demos.