Yes, the 32GB card works fine with the Fuze+. The primary advantage to the higher-class (speed) card becomes apparent when using it in a video or multiple-shot mode on the camera. On the Fuze+, even using a class 2 or 4 device, I haven’t had any issues.
The read/write speed is limited by the processor itself, as the Fuze+'s Freescale chip handles the USB transfer and memory access. The only time the transfer speed really shows itself is when you’re transferring a huge block of files, which in my experience isn’t too often. I usually transfer a few albums or books, or a group of podcasts.
For the Sansa, the basic card is perfect, especially if this is your primary use for the microSDHC. The Ultra cards are faster, but not a necessity. They will last for years, and may find use in different devices. I have seen, on occasion, Ultra cards available at prices comparable to the basic cards, especially as the larger capacity devices come down in price.
The database (all media) of the Fuze+ is handled differently than the Austria Microsystems platform Sansas. The firmware is a completely different format, and the way it parses and stores this information takes noticeably longer than the AMS machines. As many have discovered, having a large collection on the Fuze takes a while. The speed class of the microSD has little effect on this process, even though it is doing successive read / write operations; the actual database building process consumes more time than the memory operations.