Right...as long as you have a "good" loaner equivalent (in this case another MDX) then you are putting miles and wear on THEIR car so might as well be patient, and then when they give you back your car all fixed up it will have fewer miles and wear and scratches and rock chipsWhen ever I get a loaner from the dealer I don't really want my car back. I tell them to take their time because I am going on a long road trip. I think you are pretty lucky to get an MDX loaner. The only loaners my dealer gives out are RDXs and TLXs. If I were you, I would have waited it out.
Congrats on the Bimmer. I have owned them and they were always in the shop getting some warranty item fixed. My BMW dealer had limited BMW loaners so all I got was Chevrolet and Dodge loaners. Try the taste of that sometime. Good luck with the Bimmer and sorry to hear about your Acura troubles.