Jimmy,
I replaced my 1500's with 2500's about 2 years ago. I would not go back. The 2500's are very easy to use and pretty much bulletproof if you leave the rubber bumper cover on them. Mine have the off-route analysis, balancing, and startup-coastdown options installed, so I can use them for anything I was using the 1500's for. The 2500's are much lighter than a Datapac, the batteries last forever and are standard NiMH camcorder batteries so they don't have a memory and can be left on charge whenever you are not using the meter. The Enpacs have alot more internal memory, I've never managed to fill one up, and they take compact flash cards as external memory.
The screen is smaller than the Datapacs, but it is color and is very easy to see in bright sunlight or total darkness. The USB connection makes unloading and loading routes incredibly fast, my largest route takes about 5 seconds to load. Overall I'm very happy with mine. No, I don't work for Rockwell, just a satisfied user.