Regarding the NEW P-210s...
I just sold a P-210-6 (I know, I know, I must be crazy... but actually, I had a newly-purchased truck to pay for, and the P-210 represented about a 1/3 of the purchase price.)
I shipped it to the new owner's gunsmith, in Fl., and the gunsmith had a chance to compare mine (made in 1978, but bought new two years ago) to a new one. He said the old one had a much nicer trigger. Much nicer. No comparison.
I won't be surprised to see the older ones hold their value or even increase in value.
Everyone I've talked to who has worked with both the M-49s and the P-210s say the M-49s are not quite a nice as the P-210s. According to the experts (including shooters on the SIG forum), the M-49s are fine guns, well-worth the money, but not quite as nice as the commercial P-210s.
Then too, a fews of the M-49s have alloy frames -- a special production run for the Danish police forces.
I'd expect there to be some difference in quality, since the M-49s are refurbished ex-military and ex-police guns, that had a life prior to being imported to the US.
Does anyone posting here have both, or has anyone shot both, side by side? I've only seen (handled, but not shot) one M-49; it was not as nicely finished as my P-210-6; and because the P-210-6 had a "match" trigger, its unlikely the M-49 was a match in that category, either.