This attitude is an especially disappointing coming from architectural photographery workshop leaders, who leave students shooting DSLR with the impression that their DSLR equipment is so inferior as to be unusable. As I have stated many times, I work for some of the high level clientele that he does (though most of my work is local with smaller budgets) and my top flight national clients have been totally satisfied with my DSLR work. See also From 4x5 to DSLR.
Do I want more quality? Absolutely. Always. But the cost/benefit equation must meet both my client needs/expectations and mine. Buy into a MFD system? I would need to justify about a two year write off. Once you start chasing that dog, it never stops. I can do that chase with DSLRs and stay very up to date AND profitable even with mostly local clients and editorial architecture. As it stands now in terms of file size (MFD vs. DSLR is not just about file size but image quality too) a 21mp camera file meets 99% of my client needs WITH some clients complaining that the files are TOO BIG.
As per workshop instructors? We all have our varied experiences and biases. I wouldn't take such criticisms personally. Oftentimes an established photographer has a very different frame of reference than the students do. I would take the workshop and learn what fits ones present circumstances and future aspirations. In my experience, if I walk away from a workshop with two or three really valuable lessons that allow me to save time, make more money or see clearer, I usually feel like it was money well spent. But again there is a cost/benefit issue with workshops too.
Excellent advice from Kirk...can't really add much except to emphasize the cost of the esoteric digital backs and how quickly you must amortize them. Unlike the good old film days, digital capture technologies are rapidly changing, meaning that today's $40,000 MF back will lose most of it's value in 5 years because in 5 years you'll be able to replace it with a DSLR that's 90% cheaper, has equal or more megapixels, more dynamic range, faster capture, higher ISO's, lower noise, etc.
Are MF backs necessary for success in the AP business? Absolutely not! The guys at Attic Fire (see: Attic Fire) use Canon gear and their lenses are the "lowly" 24mm tse as well as the 17-40 and 24-70 zooms! They've developed a unique look and feel to their images and it is their strong post-processing techniques which sets them apart - not the gear they use. They are a busy firm with a stable of top-notch clients - mostly in the hospitality industry.
There are gear snobs and there are successful photographers and they're not necessarily the same people.