I own both. (as a mater of fact, more that one of each, if you consider the 411 (40S&W) but only one 911. It would have been difficult for me to do the deal. (the 911 was only produced for a couple of years and then replace by the 910 and I have been told it is not as good) On the other hand the 15 was produced in the millions and with the exception of the Model 10, rode more miles in a squad car than probably any other Smith. Having said that, really nice 15s are not laying on the shelf of every gun shop you go in. You have to be the judge of your trade. If you are happy with your decision(and who am I to say other wise, not having seen both guns in person) then you done good.