Hehe. No problem
This is very interesting.
Actually with some friends (and unlimited access to Alcatel's HW labs - oscilloscopes, probes, HW experts and so on) we took some time to dismantle and reverse engineer a PC PSU.
This was frightening.
Imagine that, maybe 95% of the price is made of.. MOSFETs. They build the rest of the PSU around them. The switching circuitry feeds them an incredibly dirty, spiky and noisy signal, not to mention it's way out of level. Of the remaining 5%, maybe 4% is made of heatsinks and fan. The rest is the crappiest possible condensers, diodes, resistors and coils they can find. No wonder those regulators get damn hot.
So yes you're totally right when you say one cannot change PSU MOSFETs easily...
Comparing with an indutrial-rated PSU (such as those from RSG, or others) brings no similarity.. Not even close...