??? Established Manufacturer or Take A Chance ???

If EVERYTHING is identical, I would expect reliability to be identical.  In the case of a solid state amplifier, a quality piece should last 15+ years without service (in my experience).  If that is the case, I'd save the money.

But, I would be concerned about the reliability of an unproven product with no history.  

Depends strictly on how much and one’s tolerance for risk.  Personally with bigger ticket items I always shy away from smaller companies with little or no track record.  But the devil is always in the details so anything possible.  Customer service and support matters when talking big bucks in particular. 

If you already picked speakers, then your choice of amplifiers is limited to those that have "audible chemistry" with them, and will give you the end sound that pleases you.

Absolutely established... if you are looking for nuanced quality sound. When a manufacturer has been around for decades, they have attended to the minor aspects of sound as well as first blush characteristics. If you are buying high end equipment you will be discovering nuance deeper and deeper into the sound as time goes on. You want that nuanced performance. 

As I have gotten older, I have appreciated the nuances of well reproduced sound, the gestalt, proportion and musicality. These arnt’ things you get right in the beginning. If you are looking for slam or details for the money... then newer companies. 

I have worked in manufacturing for most of my career as well. Same thing here. Learning to manufacture well is part art and science. Knowing not the put some part next to some other... even though it "should not" make a difference comes from experience... it can effect sound and reliability. 

You earn becoming a well established brand and manufacturer. This happens over time delighting many customers. Additionally, over time you establish processes and best practices that help keep you on top, again, over time. There are many “flashes in the pan” that do things well for a short period of time and who knows if they can keep it going for lengthy time. I am a firm believer in buy it once. Therefore, I would buy the trusted well established product knowing that it has earned its place at the top.