Leonardo USB Vendor/Product ID

Actually, there's a silicon bug in them 1st batch. So, they pull out all the stock from the distributors.
A bug in USB suspend mode. So, the new batch is ready in late October only.

One important thing to take note if you are using their SSOP package: the body is way much longer compared to normal SSOP package. It's like putting a 20-pin into a 24-pin package! Other than that, they are okay and way much cheaper. The IO is 5V tolerant (up to 6.2V although not specified in datasheet).

I've already used several in my projects,

Frank, have you tested the most minimal version (FT230XS) using the RTS instead of the DTR to perform a reset on Arduino?
Didn't managed to grab the FT230XS before it they pull them out of the stock.