Theoretically speaking, your firing pin probably won't last as long. The SA hammer strike is actually quite a bit harder than the DA hammer strike.
I would like to see some quantification given to the statement 'quite a bit harder'. What exactly are we talking about here? 10% harder? 20% harder? 50% harder?
Does anybody remember when S&W went to the short throw hammer, in 1948? Before that, the cocked hammer position was significantly farther back than with the newer short throw hammer. OK, everybody is I hope familiar with the fact that because of the mechanical design, the hammer MUST be pulled back farther in single action than the release point in double action. That is a given. S&W realized that since the hammer spring had been compressed enough in double action mode to fire a cartridge, pulling it farther back to cock the hammer was wasted energy. So the short throw hammer was born, and was phased in over time across all models.
Now, I have just been fooling around with an old long throw 38 M&P, and a new (1974) short throw Model 14-3, launching pens at the ceiling in double action and single action mode. I want to tell you, the firing pin may be striking the pen slightly harder in single action with the short throw, but danged if I can measure it. The pen is smacking the rafters in the basement pretty hard in both cases, and I don't have the instrumentation to get a measurement of which way the pen is hitting the rafters harder. Yes, the old long throw M&P does seem to be launching the pens more vigorously, but that is not a fair comparison because the springs are not the same in the two guns.
Jim Watson makes a good point that with a weak spring and CCI primers, which are harder to ignite than most other brands, a single action hit will often light off a primer that does not fire from a double action hit. But that is a marginal case, with a spring that is just barely delivering enough oompgh to set off a CCI primer in Single Action mode.
Back to the original question, no, for a quality revolver, there will be no long term effects firing a double action revolver in single action mode. They are well enough built that a quality revolver can take a lifetime of single action firing without damaging the gun.
P.S. Yes, I do most of my shooting with my double action Smiths and Colts in single action mode. Try as I might, I just cannot hit a tin can at the 25 yard berm reliably in double action mode.