Sammy and Dominic were great guys and knowledgeable in hydronic systems and forced hot-water boilers.
I moved here recently and have found that most plumbers in the Albuquerque area don't have a clue, especially when it comes to hydronics. I wasted my time with clowns from one of the big HVAC repair companies who claimed they were certified to service NTI boilers (hint: they have all 5-star reviews on Google+ and Yellowpages, which is statistically improbable, i.e. they pay friends and family to write fake reviews).
I called NTI and found only two companies in the Albuquerque area are actually certified to work on their boilers; Welch's and Big M, and Welch's doesn't work on residential systems.
Big M was able to get someone out within 2 days for routine maintenance, and the same-day for an emergency repair. There was a minor billing issue, but it was resolved immediately. My rating is 4.5 stars. The only criticism I have is that their markup on materials is high (as is that for most contractors) and their labor rate is on the high side. In my mind, well worth it for someone who actually knows what they are doing.
I will likely use Big M again and would recommend to friends/family.