I would agree there are other quality regulators out there dollar for dollar. But, if his local shop and service center only repairs Scubapro and ..... then that is really what his choices are going to come down to. That isn't saying they won't be able to service other regulators by other brands. Most shops prefer to service what they sell as it helps balance the books at the end of the year. Scubapro has a good stake in the market, with free parts as long as you service them every year. Really it does come down to preference.
I would say you are going about it the correct way. Do your research and then spend your dollars. No matter what you end up buying it is very unlikely you will regret your purchase. Another idea would be to rent a set of regs. Try out as many combinations as possible before you buy. You might find that a 250 is too large for your taste, or that an s600 adjustment knob is too difficult to use with gloves on. Most local shops are pretty helpful, go discuss your hesitations with them and see what they say. If you are set on a SP 1st stage I would personally match it with a SP 2nd so that I could send the regs in for service together to my local shop. Also SP and APEKS have world wide service, so chances are if you travel and something happens a local shop in the area of travel could help.