Just to be clear, the one time I did get a step beyond the "Sending information to Apple" stage, and it went to the "Waiting for Apple to deliveer Itunes Match results", the end result was that it gave me an error message and ended that attempt. So basically every single time I attempted iTunes Match without having cleared the iTunes cache first, it failed.
Every time since then that I tried clearing the cache I successfullly completed iTunes Match. Now maybe the servers just happend to be available at those time, which is why I'm saying the problem may not be solved.
But, BUT, since clearing the cache those times and connecting to iTunes Match, I also tried completing iTunes Match without having cleared the cache, and it just hung up on me and give me the error message. After that I went back to clearing the cache, and it worked.
So you decide for yourself whether you want to give this a shot or not. If you think it's a waste of time, no big deal to me. Maybe I did get lucky and fluke out, I don't know for sure. But wow, if I was you and as frustrated as I had been before, I would give it a shot.
And someone said something about how resetting Safari ooesn't have anything to do with iTunes cache. Well they are connected whether you would like to believe it or not. iTunes relies on the internet to connect to Apple's servers, and so when I reset Safari it must clear a setting that iTunes looks for when it connects to the iTunes Match servers.
I may try to connect again tomorrow during a peak time so I can confirm whether it continues to work or not.
Good luck.