My opinion is this, coming from a weekend/evening trainer who can't afford a pro. 1 dog in its prime running master tests, Q, AM and 1 puppy. Then potentially an old dog, prime, puppy depending on the timing.
I'm working on #2 now. Biggest thing is be able to dedicate time and money or the dog won't reach its potential. I would give the first dog a few years and re-visit the second dog unless you are financially capable of becoming fully "addicted".