Yep, I made the switch a little over a year ago. My primary motivation was the mounting system & brake. I thought they were vast improvements over the 1000's. The 1000's are solid, but not as good as the 1500's. You'll have to get used to a couple of things, one is the 360 degree rotation. Around the throat, you'll send the string under the arms rather than over. This is a good thing as there is less friction going that way. You'll also need to use your diabolo when stringing. The other thing is weaving. I had gotten used to the tension head also acting as a stop for the turntable. When using the 1500, there is no stop so I had to alter my technique slightly to accommodate that.
The mounting system on the 1500 and adjustments are, in my opinion, way better than the 1000. With the 1000, your turntable lock is underneath it and after about 15 years stringing on it, it finally bit me. I forgot to lock the table and as I finished the last main on a buddy of mine's APD, I head a pop. A $200 pop as it turned out.
With the 1500, you'll never forget because the adjustments are all up there with you. As mentioned, I think the brake is superior as well. The disc on mine was slightly out of adjustment and with the 1500, it's a gear and knob arrangement which is simpler and again in my opinion very effective.
The clamps on the 1500 take some getting used to. You have to remember to lock the base, but once you do, it's good. It is nice to not have to remove a glide bar when doing crosses. I also have come to really appreciate the flexibility double action clamps give you when stringing. They are more flexible when doing ATW and or other things. The clamps on the 1000 are aluminum and aluminum is soft. Mine wore out after about 15 years and cost $70 each to replace. The clamps on the 1500 are steel and I don't think they'll wear out. Replacing them is $130/each. Cleaning them is a breeze, taking them down is much easier than the 1000 and they clean up really nice.
The 1500 is a great improvement over the 1000. It appears the manufacturer made the right improvements without over engineering the final product. In other words, they did it right. If I were to upgrade, it wold be to an Alpha Ghost, but after talking to JC, I think I have all the machine I need.
FYI - I also use a Wise.