Sony PRS-T3 MicroSD card

Hi All,

I'm considering getting a MicroSD card 32GB and just dumping my entire library onto it, so I will rarely need to connect to the computer except for the occasional new purchase.

Is there any downside with the SD card instead of internal memory?
Does it end up being a lot slower to go through your books, turn pages, etc or any other operation?

Also how do the Sony readers handle navigation of a large library?

Many Thanks