I'm running my XPR5550 on a Yaesu Linear power supply but only because that was what I already had. It's probably overkill for the task. I'm running 3 mobiles and some accessories on the same supply using a Rig Runner DC power strip. My understanding of switch mode power supplies is they are smaller, lighter, and cheaper but they can generate some noise. Noise is more of an issue on the HF bands. I think you would be fine with a switch mode power supply to run the XPR5550. The current drain is listed in the Basic Service Manual as 14.5 A max. Find one that can do 15A continuously. If you're going to run other radios off of the same supply at the same time you might want to go for a 25A or 30A rated supply.
I have used several switchers [Samlex, Astron, DuraComm, & MFJ], & they all work great. Some might generate rx noise on HF, but not on VHF, or UHF. On my equipment, XPR4550, it draws more current in analog, than digital. Low power in analog draws 7 amps, while in digital, only 4 amps. A 15 amp supply should be fine, as it would be a rare occasion one would xmit on 2 radios at the same time.