If it ain't broke, why fix it?
As far as diesel purge....never did it. I have owned about 30 benzes, mostly diesels. When I get a new (to me) one I change oil and all filters, install bilsteins and michelins and check the brakes. I would before too long purge and renew the brake fluid, too. I would also probably treat the fuel with injection cleaner and biocide, just to be sure.
I would check the belts and wash and wax it and enjoy.
About fifteen years ago, I bought a new (to me) '83 240d. It was a nice clean car with, IIRC, 170K miles or so on it. I pulled it in the garage and changed the oil, filter, fuel filters and air filter. The next day I headed for canada on a full day drive. My wife said..."you sure you wanna take that new car on a long trip like that after just getting it?" I said..."sure, its fine". It was.
I have never ran a baseline compression test on any motor of mine. I have only done it when a problem is suspected or as a prepurchase check.
If you feel the need to do something, I will check....I am sure one of mine needs a thing or two.
Tom W