I bought sleds for access riding last year.
All of the info posted is accurate (save one bit, I've not gotten hooked on sledding).
I started with an 03 Summit 700, 144" track. Before I even skied off it, I realized two things:
1. They're WAY harder to ride than you think.
2. A second sled is mandatory.
I rode initially at an area fairly close to my house; good ski terrain, difficult to access on the sled. At first, I went there just to ride it - going "just for a ride" illustrated the need to learn HOW to ride, AND clarified the "second sled" bit - even early season, the sled took me WAY farther than I wanted to walk out, and getting stuck is guaranteed. Getting unstuck is normally not a problem, but I've not had anything Bad happen yet - roll it down a steep hill, leaving it upside down against a tree, or in a creekbed, or or or - possibilities are endless. Get two, or find other people. I guess if the car is ALWAYS downhill, and you have skis/boards, maybe....but....get two.
I bought a 99 Skidoo Summit 670x for a backup. Both are really solid sleds, both are capable of towing two skiers on groomed runs (Vail Pass in CO). I've not tried much 2-up riding on the 670, but the times we have, it did OK.
They make similar power. Both make just enough. A friend of mine (and the classified ads) scared me away from SkiDoo 800s - virtually all of them had "new motors" or "new pistons" or "needs a....." included. I wanted something reliable, and my friend, a SkiDoo mechanic, recommended "anything but" an 800 (in my price range), and more specifically, a 700 or 670x. I see that you (the OP) bought an 01 800 - same basic sled as my 700, but with the bigger motor. In the words of my mechanic friend "if you HAVE to have an 800, do a top end every 1500 miles." Dunno. I've run across plenty of people who have had good luck with the SkiDoo 800s (pre-"R" motors, 07? and earlier), but it seems that most have had them blow up. Maybe do a top end out of principle? Dunno.
I'm happy with the power, for the most part. Two up on softish run-in trails is tricky; sometimes, more power would likely help - but honestly, I'm pretty sure the 700 (the primary tow-sled) *can* do what I'm asking it to, I'm just not asking right (see "way harder to ride than you think"). I think that more power would make it easier, but watching other, more experienced sled-skiers do their thing, there's a chunk of skill that I've not yet developed that will make the comparative lack of power a non-issue.
I am putting a 156" track on my 700 this fall. I do believe that'll help when the skiing gets really good.
If you're doing it at Vail Pass or Buff Pass, where there are groomed cat-roads in place, a tow rope is easy and works great.
If you're making your own trails, learn how to ride two-up. It is tricky. Burn them in solo. On the steep bits in particular, I've found that it is better to make an "up" path and a "down" path. Seems to stay smoother that way. Use the flattest path to the top possible. Don't stop going uphill, loop around and get back into your track. Speed is your friend. Try to go straight up hills (single-fall-line if possible), leaning with two/sidehilling is tricky. Try to make a path that gives you a good run at the hill.
Racks - I ski. My racks are simple and they work; a 2x4 bolted to the tunnel with two square, coated hooks for hanging ladders on your garage wall. The hooks point "in." There's a bungee cord near the front of the seat, rail to rail. Tip under the cord, tail inside the square hook, short cord tying the tails. I've rolled the sled down a steep hill (four or five barrel rolls) with the skis on, no damage to the skis, they stayed attached. The Cheetah Factory Racing racks look awesome, and I might get a couple this winter, but I was feeling it in my wallet last winter after buying two sleds and all the other junk I did not have.
Ditch the windshield. It WILL break when you roll it, and rolling it is often the fastest way to get unstuck (thanks, Kaleb!).
Carry a spare belt, plugs, etc etc etc. Carry enough junk to stay comfortable overnight.
Beacon/probe/shovel + education.
It is fun. It adds a ton of complexity to a ski day. That said, I skied powder every day last year......well worth the effort, but don't even bring the skis the first couple of times out.
Iain