Well the 316L steel was used by Rolex till the early mid 80's. Then Rolex switched to 904 steel because of better corrosion resistance and that had also an influence on the rolex price. The 904 steel is more hard to work and refinish than the 316l steel.So it also explains why Rolex costs so much since the early 90's.
Well the smp was born in 1993 and that time it was fitted with the cal 1109 (an engraved eta with no modification or improvements) then in 1995 the smp was fitted with the cal 1120 (a reworked eta with an improved winding system, rotor and finish). Breitling started to manufacture the colt ocean in 1994/1995 but fact is that the watch is nothing exceptionnal and is horrendously expensive for a watch fitted with an engraved eta 2824-2 with zero significant improvements. IWC is a particular case, they have a whole stock of parts for their version of the eta 2892-a2 and even for their own inhouse movements. For servicing vintage Rolex, you have to know some very good independant watchmakers and if possible former rolex watchmakers. I have however read that Rolex will make a vintage service division.