Without the slightest reservation I would suggest that if someone was in the financial position to do so, they should go with a Euro Sauna Lumina.
The reason: as far as I know Euro Sauna is the only manufacturer in North America to employ Philips' Vitae lamps in their units.
Philips' sells their Vitae emitters to a prestigious German manufacturer (EOS)which in turn gets them to Euro Sauna.
Here are two links invaluable to someone thinking about purchasing a "high-end" unit (such as Sunlight). The first is Philips' brochure on their emitters; the second is an overview of infrared saunas.
Insofar as Sunlight goes, they've been a marketing machine and branded well. Esthetically, their units have a lot of appeal--great eye candy and a few nice accessories. I don't believe, however, they are the "technology leaders".
Until they go full-spectrum with their emitters and hang around for a while (EOS has been in business for 60 years)they're the new kids on the block and they have a way to go to catch up with the real alpha-dogs of the industry.