I did - be carefull - might not work!
I ordered and got my 4GB card last week (mobymemory). While the card is recognized in the phone, my phone keeps crashing ever since. When i put in my mobymemory 2GB card, my phone doesn't crash. I also noted that the card is getting corrupted quickly in my QTEK 8310 (using chkdsk in a cardreader to confirm).
I mailed HTC and they said that 2GB was the maximum supported by my smartphone device. I stated that on their website they claim miniSD up to 12GB was supported, but they say that is a typo on their website they will correct soon.
I also mailed mobymemory but haven't got any response yet. Still it might be that i just got a faulty one.
I am now on my latest experiment. I partitioned the card in a 2GB (2048MB) partition and the rest (1.9GB); my phone recognizes the two storage cards (second is now named 'storage card2'). However, i already had my first crash quickly afterwards (using navigation).
Right now, i am formatting the card to FAT instead of FAT32 (still partitioned).
Running out of options, will keep this thread updated.