As far as I have read, only Overland Navigator does it elegantly *and* is able to work with the 710's custom icon set.
By elegantly, I mean it will age out stations on the display, while any other tool will just make waypoints that you will need to delete later.
Given that ON is a Windows product, that is your largest filter for what hardware can be used.
I have an Itronix DuoTouch refurb tablet from ebay I have been using for a couple years. It is based on old Intel Pentium (centrino?) technology and runs around 1GHz. It is ruggedized, does't break the bank, and has worked great for mapping (using TOPO! mainly). The 40G drive finally gave up, and I was worried about upgrading as there are extra ribbon connectors to the drive (for S.M.A.R.T. related monitoring?), but leaving those connectors off, I have a 120G laptop drive I had laying around and now working fine. Went through the recovery process and WinXP tablet edition is back up and running.
RAM also makes a mount cradle just for this Itronix unit.
I am still watching for a new tablet and would like to get something with a larger and brighter display (the Itronix is 7" or 8" touchscreen). It can't be too expensive as it will need to be somewhat disposable given the environment of traveling in rough dry areas. My first tablet was bought that way, was barely enough CPU to do one task well, and lasted 2-3 years. It was a good unit, but way off-brand.
I haven't found software yet for Android OS that allows what I think of as basic map editing, so that alluring range of Android-based tablets that are generally cheaper does no good (yet). Natl. Geo has written me saying they have no plans to port their 24K State Series software to Android.
Using Google Earth for map editing is looking very promising lately, so it is very likely a path could work where you do your planning and editing in GE, and then export to GPX or KMZ/L (and/or then convert to some other format) for an Android-based tool to read. It is also possible that GE will add more features to their Android app, to make it an all in one functional tool not as dependent on a cell signal for map data.
For me software is still a huge driving force in finding appropriate hardware. But moreso it is what you need from the software that is the largest factor. Most people seem to be ok with just having a map and a marker of your location, and maybe adding waypoints. For me that is the barest of minimums. I also want more map detail with historic info on the map so I stick to USGS based 24K/100K/+ map data. Those decisions exclude me from 90% of what is on the market. Add APRS to that and it is even more limiting, depending upon your expectations.
The phone or Garmin 60 is my on-highway navigation if I need it.
