@SteveW - With a DA and the orbital action of the polishing head you don’t really get a build up of heat that you might get with a rotary polishing machine. Also, if you apply too much downward pressure with a DA, the polishing head will stop spinning. Therefore, I’d say there’s minimal risk of damaging your paintwork, provided you use an appropriate combination of pad and polish and your car hasn’t previously been polished to death by a former owner.
As
@bruceR has said, watch a few videos on using a DA so you can familiarise yourself with the techniques to use to get good results. Also, always start with the low cut polish and a softer, low cut pad so you remove as little clear coat as necessary when you polish. If that combination doesn’t give the results you’re looking for, work up to a slightly more aggressive polish and pad combination until you get the results you want.
I bought my DA about 7 years ago and it’s more than paid for itself - I’ve used it to polish both of my previous two cars twice each. In addition to polishing the whole car, it’s really useful for ‘spot‘ corrections - e.g. removing clear coat etching from bird poo and scratches that pass the ‘finger nail test’ (i.e. they’re not too deep for your finger nail to catch on, so should polish out). It was a little bit daunting the first time I used my DA, but after polishing the first panel, I felt confident enough to carry on and complete the job without trepidation.
There‘s a really good, very comprehensive
guide to machine polishing using a DA polishing machine at the link below, which is worth a read;