Park,
Welcome. I enjoyed your automobile analogy. Sig and Glocks are great and I concur that they are far better for shooting multiple boxes with greater ease and comfort than the R9. However, nothing beats the R9 for concealability and you are, after all, shooting a serious cartridge in a small package.
The only downside to buying consecutive S/N guns is that they retain their value more if they are made into "safe queens", if that is the right terminology.
You don't impress me as a guy who wants to keep the consecutive R9s away from the range. Don't know if you are still considering the second R9 but those are my thoughts.