Never used 4500, but 4000 is my favorite polish.
You can expect it with '2 degrees' more cut than 4500, but the same gloss.
You can expect it to act as an AIO polish for mild / fine defects using either a finishing or a polishing pad.
You can expect it to correct defects using a finishing pad on soft paints.
I run it generally on speed 5 or a bit more on the Flex 3401, using Smack's technique (please, just ask if you need further tips on this).
Here are some threads I have using this polish:
Using gray/black finishing pads and SF4000
http://www.autogeekonline.net/forum...-full-detail-pbl-coating-coating-booster.html
Using many colored pads (white, blue, etc) with SF4000.
http://www.autogeekonline.net/forum...ll-detailed-pinnacle-black-label-coating.html
When need to 'step up to even higher cutting pad' while trying to stick with SF4000, I generally prefer to use FG400 on white pad instead of SF4000 on an orange pad.
Being it a very fine polish, you can expect it to cut only on soft paints. For harder paints, you may use it on white pad to follow a compound you used on orange pad or MF pad or Wool pad, as a refinement, a finishing approach.
I always start my test spot with it because if it works, I'm in heaven. It dusts very little to none, offer great lubrication, have a good working time and finish really, really glossy.
You'll like it, I'm all-in on this bet.
Kind Regards.