I tried to use Avemco on three separate airplanes over a 10-year period. Every time, their quote was very timely, but ultimately non-competitive. Last time was on a '65 Citabria 7ECA, where their quote was $1800 per year, versus $795 for the exact same coverage from Old Republic.
Still, I thought "Well, I'll give them a try on the experimental Rans S-6ES..." Seven days (and counting) without a human response. I did, however, receive an automated response thanking me for filling out their online quote request, and telling me they needed some additional information, then asking for EXACTLY the same information I had already provided – literally every single field was identical to the online app I had already completed.
Not the kind of (non-) response that gives you confidence they will be there if/when you need them...