This is not quite what you were asking, but for what it's worth, just wanted to throw this out there. I have not had success with oral meds (Viagra,Levitra,Cialis), nor have I tried MUSE.
I have had success with penile injections of Quad Mix, but dislike self-injectioning. What I've tried successfully is a new drug that is on the market called TriMix gel.
The drug is mixed at the time of use. The gel is squirted into the urethra. I have experienced no side effects common with MUSE, like burning or itching. And it has worked so far.