Someone else mentioned repairs. If you want to fly all over the Americas (not just the U.S. and southern Canada), then spares and repairability at remote airports will be important. Understood that you want the BRS, and that's fine, but otherwise, try to keep everything as stock as possible so that you have a better chance of finding parts locally or ordering them quickly AOG when you're stuck somewhere — in the long run, that will probably save you more time than a couple of extra knots here or there.
But going against my first advice, diesel (and Jet-A) are much more widely available than 100LL outside of the U.S. and southern Canada, so if money really isn't an object, a diesel-engine conversion could pay off big. For example, if you fly far enough north in Canada and you need 100LL, other pilots have told me that you sometimes need to make private arrangements with local band councils weeks in advance, buy it by the barrel (42 gal), and hand-pump it yourself. That may also be true in smaller towns and islands as you go south in the Americas. But there's always diesel, and there will be Jet-A at any airport that gets commuter flights.