I own a Tron preamp, not the Syren, the Comet, I don't think the Comet is made anymore, but it was the 'entry level' Tron. I also had an Eastern Electric Minimax for a while. I think you are WAY off base regarding reliability, build quality,etc.; my guess is that it is just the opposite, these brands are MORE reliable and better built than other more 'popular' brands. The most likely answer for why you don't find them around at lots of dealers, or why they aren't 'growing' (this applies to the Tron at least), is that Tron is a one-man operation, each preamp is hand-built by the designer. Supposedly it takes about 70 hours to build one preamp. Do the math, two weeks to build one preamp, 52 weeks a year, makes a grand total of 26 preamps possible. Tron also makes amplifiers, phono stages, etc.; there are only so many hours in a day.
When you buy a Tron Syren, a Messenger, an Epifinia (BTW, I live about 90 minutes away from Emotive Audio) you are buying a high performance limited edition piece made by a perfectionist who cuts no corners and who (I am speculating here) doesn't necessarily want to hand off the work to someone else because there is no guarantee that the same level of craftmanship will be adhered to.
I also own a fair amount of David Berning equipment. David has none of his amps in brick and mortar dealerships. He builds EVERYTHING himself, and he also has a full time 'day job'. How much can one guy do?