I run a PDA with Delorme both Pocket streets and Topo 3d V.5. The maps are completely uploadable to a PDA and can interact with Garmin products. There is a transfer option to move it to the PDA or GPS. Or you can save it and then copy it to the device. I use mostly the Topo wich works great as a street planning software as well as a Geocaching product. No switching maps, no switching computers or laptops. Just drop a waypoint find the closest street and plan the trip from start to finish. Its that simple. It allows me to track my hikes, gives me voice commands on the road, and if i'm out and about and someone says "lets go caching" I just punch in the waypoint coordinates and it puts me ontop.
I started reading this forum to see if there was anything better for me out there, but after 3 hrs of scanning this forum i've come to the conclusion that I have the best option. No problems transferring waypoints, maps, even someone elses log files. I can plan on the fly. Just the other day my boss asked me to go to a conference that was starting in an hour. No problem punched in the address of the hotel, started a trip plan from finish to start and reversed it and off I went. A half hour later I was walking in the door of the conference. With time to chat and get coffee and snacks.
I read the isssues with standalone gps units and I just don't see the reason for having a unit that only does one thing. I can jump on the net and get waypoints from Geocaching.com or even if it was e-mailed to me or as in the past given to me over the phone.
The only downside I have is weight. I use a Dell Axim X5 wich is probably one of the heaviest PDA's out there, but it offers 2 memory card slots. One for the CF gps unit and one for maps, waypoints and even downloaded html files. I don't think any other PDA can say that. I also use a OtterBox for outdoor protection. I can hang it from a belt loop or a pack strap or mount to my bike. Its still lighter than a laptop.
Sorry its a long winded response but I thought you might want to know this guys opinion.