Let me begin by saying that I haven't had the 1000 long enough to get a solid opinion of it yet. It is an Ultra and not the Power Master model. I bought it on E-bay recently for a good price and had it refurbished at the Garrett Factory to make sure it was up to par. The one thing I have noticed is that it is not as "hot on the lower conductivity targets. I have to listen more closely to the mid tones as they are not as sharp as what I'm used to on the 1250 and 250. The higher conductivity targets are loud and clear so not much difference there. I plan on comparing it to my hunting buddys 1000 Power Master to see if we can tell any differences there might be between them. I can't really say much about depth comparisons as I haven't logged that much time on it yet and to be fair I won't be able to do a real side-by side due to different coil configurations on the 1250 and the 1000. Right now I have a 5" Hothead Ferrett on the 1000 as the stock coil really seemed sluggish and I have the 7 x 10 elliptical on the 1250. Apples and oranges there. I might hook up the stock pizza coils on both one day and give them both a test run, just for fun, though.
I believe the biggest thing between the 250 and the 1000 is the response recovery time. That little 250 doesn't miss a beat. When I first got the 1000, I took it to a school and with the stock coil attached, worked a parking lot median so I could be sure that I would be covering a defined area. After going over it with the 1000 and recovering a respectable amount of coins, I rigged up the 250 and worked the same median and recovered coins that the 1000(and probably somewhat due to my unfamiliarity with the 1000)had missed. Most notable were the amount of nickles that the 250 really bangs on and the 1000 hardly seems to notice. I do get a response from them, but not the hard hit of the 250 or the 1250 for that matter. Now, all that being said, I still want to compare it to the 1000 PM my hunting buddy has, as I am not sure it is 100%, even though it has made 2 trips to the factory.
I'm not sure I answered your questions, but these are some things I have noticed so far. I'll keep swinging and digging and having a blast doing it, no matter which one I have in my hand.
Happy Hunting all!!