I looked at the N560 carefully just now. It looks really good. Unfortunately it doesn't have GPRS/3G and there are no SD GPRS/3G adaptors that I can see (though no shortage of people waiting for one).
Currently I use a CF GPRS card (RTM-8000) and a CF GPS card (HI-305) in the HP4700, which has CF and SD slots.
Most GSM-enabled devices are phones, and some of these do have GPS, but not wifi. I would much rather have GSM (GPRS/3G) than WIFI - the probability of getting connectivity (for aviation weather, particularly) at a random location is far greater than with WIFI.
The HP4700 does exactly what I need and does it well. The problem is the auto power-up feature, which ensures the battery is flat most times I need it - even when I keep it in a protective case.