I'd like to share my recent experience. for a few months i have been running nookie froyo on a an 8 GB samsung class 6. it served all my tablet needs, and i liked it so much i never really was motivated enough to even try honeycomb when the devs released it.
This past week, i decided to start browsing the forums again with the intention of throwing something on my new ADATA 16 GB class 10. I put a dual boot phiremod/honey image on it and gave it a test drive. everything looked real nice, but the more apps i added from the market, the more force closes i would get. So i tried CM7 on the same SD, Same results. force close every minute. Market, Launcher...force close. unbearable.
So i used winimage to create an image of each of them (instead of re-installing clean). I then put the dual boot phiremod/honey image on the Samsung card and it works with NO force close issues. Ive set the phiremod up with everything i need, including netflix, and it's fast and friendly.
I'm not in such a hurry to load apps into honeycomb though, but when i've bumped around on it, there were no issues with speed or stability.
There's a great thread on xda where one member shares his moment of clarity , after using a CLASS 2, 8 GB sandisk card.
SD Strange-results - or - How I learned to love CM7 - xda-developers
read up before wasting money on an ADATA class 10 like i did. good luck.