First of all, let me note that the card that comes with the phone is a SanDisk 2gb MicroSD card, NOT MicroSDHC. Check if for yourself if you dont believe me. Now. I ordered a Transcend 16gb Class 6 MicroSDHC card from eBay last week, and i've been playing with it ever since. And let me tell you, the performance on my Hero has been BAD with it in several ways. First of all, it does NOT improve overall speed of the Sprint Hero. I bought it mainly it enhance the experience of the Music player (to make the music app faster) but I can assure you it is the SAME (if not slower) with the class 6 card compared to the stock card. And one thing I have noticed, which is very very annoying for me, is that whenever I have the class 6 card in my Hero, it takes long for the phone to wake when you press the menu/end buttons. Like say your phone is asleep, and you press menu/end buttons. Sometimes, with the stock card, it takes a second for the screen to come on. And that's ok. But with my Transcend class 6 card, sometimes it takes up to 3-4 seconds for the screen to turn on. I did some rigorous tests and experiments to ensure that this wasnt merely my imagination. I even, at one point, thought it was my phone that was the problem so I exchanged it for a brand new one at Best Buy and the exact same thing happens for my new Hero. Does anyone know if the Hero is supposed to not work well with MicroSDHC card's as opposed to normal MicroSD cards? PS - I tried formatting the class 6 card on my computer using 32k instead of 16k but no help from that. Still same results.