I've used fina for more than 16 years now as I am very inclined to MPB. I've stated many times in here that fina is the only reason I still have a full head of hair.
From a combined sample population of more than 16,000 users, a recent meta-analysis placed the reports of sexual side effects at less than 2% of the subject administering the drug.
Factors that increased the occurring of sexual side effects included: smoking, drinking, pre-existing sexual issues, and generally poor overall health.
So, if you are healthy, don't smoke, don't drink, and have not pre-existing sexual issues, you are very unlikely to encounter any sexual side effects.
Of those subject using the drug who report sexual side effects, less than 20% of that 2% report sexual side effects that last for more than a year.
Again, that is a small percentage of a very small percentage.
As the OP mentioned, fina should be used for test only users (and EQ and some DHT AAS in limited amounts). If you are using deca, the concurrent use of fina will only accelerate MPB. If you are using Tren, Dbol, A-bombs, there is nothing that will prevent those drugs from accelerating you MPB.
As OP mentioned, Rogaine foam is a great option that is cost effective to be used concurrently with fina. The foam works much better for temporal recession since it says on the frontal scalp area much better than the old liquid Rogaine.
I use them both and strongly recommend them to anyone who is concerned about MPB