I recently came across a great deal on used Magico S5s, but they were in Florida, and I am in CA. Since Magico is up the road, I sent them an email asking if I could have them shipped to Magico, and they could check them out. They never replied. I bought them anyway, and they arrived unscathed, and sound freaking great. I haven't even looked at my HT since I bought these. All my spare time is spent listening to them.
Of course, in this case I wasn't buying from the manufacturer, but I was a little irked they didn't reply. Then again, they have replied to other emails I sent asking other questions.
Anyway, if it was an unknown manufacturer who didn't reply I probably wouldn't buy. If it were a well known manufacturer with a great product I wanted then I probably would.