Is there a big performance difference between the 16702A and 16702B model?
16702B seem to go around double/triple price than 16702A models on ebay...
A 16700A or 16702A normally has either 64MB of base system RAM or 160MB of system RAM with Opt 003 installed. There are some late production models which have either 128MB of base system RAM or 256MB of system RAM with Opt 003.
A 16700B or 16702B has either 128MB of base system RAM or 256MB of system RAM with Opt 003.
They all have the same speed CPU. I have never tried to measure any possible performance differences between 64M, 128MB, 160MB, and 256MB of system RAM.
Other difference are 10Mb Ethernet on the 16700A/16702A vs 10/100Mb Ethernet on the 16700B/16702B, which might make a big difference if you need to copy large data files between the LA and other systems, and the built in CD-ROM drive in the 16700B/16702B which really only makes things easier if you need to reinstall the software.
I wouldn't pay a large premium for a 16702A/B over a 16700A/B unless you really need a self-contained system. The built in LCD is only 800x600 and an external LCD monitor at 1024x768, 1280x1024, or 1600x1200 can be a lot more useful.