Class 4 SD card experiement failed ... but how about Class 10 ...

My experiment with bringing just the Class 4 SD card home instead of bring the whole M6400 work machine home was failed completely.  The performance was slow and sluggish.  The SD card will disappear once in a while, and copying files from the card back to the machine is terribly slow.  And then there's a lot of file corrupting and I got prompted to "fix disc" a lot of times.  I have roll back to using the machine itself.

At first I thought maybe using a Class 10 SD card will ease the problem, but on the second thought, I think the whole SD card thing to replace HD just doesn't work at all, just forget about it.