Alright. don't forget to report back after some use and let us know how you like CoPilot.
I've been running Google Maps and Navigation on my Samsung Galaxy Player (micro-tab) with wifi-only and GPS. If you load directions from home on wifi before you leave, and hit Navigate, it locks it all in and then when you lose the wifi signal the navigation stays active. Pretty good. Every once in a while, and I can't exactly figure out why, if Navigation goes to the background, when I make it active again, the directions are gone and smart navigation is therefore gone...I still get my GPS location on standard Google Maps but no more navigation. Certainly if I shut the device off, it will lose the directions/route cache. If I hit the master Navigate button at the top right, it goes and tries to find new navigation driving directions. Without data, it can't do this and I'm pooched. Can't get back to the driving directions that it should have cached already...so I have to be wary of not making that mistake.
Several times when I have lost the directions "cache" I have managed to find a coffee shop, Panera, Starbucks, etc...picked up wifi, and got my route back. Bit of a hassle but if I really need the route, it's not too hard to find wifi. And for some reason Navigation will not hold the route and let you reverse steps for the return trip. I'll need to go grab wifi somewhere for that. Even driving around on some surburban streets you'll find unsecured wifi all over the place. (Try Wifi Analyser app. Free. Very cool. Displays a real-time graph of all wifi hotspots in your vicinity, with signal strength, with an asterisk next to those that are unsecured.)
Anyway, this system is ALMOST OK for me. Would be best to have offline Google Maps/Nav package! Lacking that, I'm going to wait a while and see if it's worth buying CoPilot or Sygic.
By the way, it is surprising to come across zones where no GPS satellites are visible whatsoever...sometimes up in NH, VT, MA, it's quite a few miles. (Try the app GPS Test. Free. Analyses available GPS satellites, strength of each, day/dark zones on earth, speedometer, altimeter, and accuracy readout. Very cool app, again, for free.) Typically there are 7-10 running. Sometimes fewer, sometimes as many as 14 or so. Sometimes most of them will be weak signals, sometimes most of them are strong. Lot's of variability. Obviously the more satellite signals you are locked onto, and the greater their strength, the higher the accuracy you are obtaining from the system. (it varies widely)
Cheers.