Jags - I have a Garmin 800 which is the model I understand the Tour version is based on. If I have this correctly, the Tour is an 800 base unit with none of the additional 'bundle items' so no extra mapping, no extra memory card, no HRM and no Cadence sensor.
I had a quick look at the base unit maps on a Garmin show stand and decided I very much preferred the OS 1:50000 set which came in with one of the more expensive bundles. I also went for the HRM and Cadence sensor - mostly because I like the analytical side of our Sunday Morning whizzy bike runs - but also because it was a good deal in a local bike shop.
On my Thorn I don't bother with a cadence sensor, and sometimes not the HRM.
I guess the value of a bundled map set over the included base map is partly down to opinion and partly whatever is available for your part of the world. When we went to Jersey in July I just downloaded a free map of the island and had no problems with that - quite how I would have got on downloading a much bigger area I don't know.
In use I find the screen is a little small for reading the map as I go along, but the turn by turn directions are ok. Just be sure to set them on for the route you are following. They might not be on by default. I turn the alarms off on mine as otherwise it buzzes & nags about cadence (too slow) HRM (too high) and off route when I take a detour.
I have used mine on SkyRides and would be happy to use it to follow a route I was unfamiliar with.
Garmin Connect (www site mapping utility) is not particularly friendly for route planning, but the after-ride route analysis is good, (just my opinion!) I find map my ride or ride with GPS easier to use for planning routes. Loading a route to the Garmin is easy - just copy the file into the new routes folder and it will be 'loaded' when you select it for the first time. You can store several routes and so divide a tour into days etc. Probably worth checking the tour does have an extra memory card slot - just in case you want to store extra maps and/or routes.
I've not had any battery issues, a normal 3 or 4 hour Sunday morning might get to ~60% charge from full. I tend to swap screens quite often so I probably over use the battery.
Most of the mapping sites I have tried work well with routes stored in mine, so when I go out around a familiar loop I let it keep tabs on where I go and how fast and then review the data when I get back. I tend to use Strava as, being an engineer, I have failed to grow up, act like a 10 year old (occasionally) and there are a couple of local hills I like to test myself on .... que story re a visit to my GP about chest pains .... it was acid reflux, and he assured me I am quite healthy for my age, apart from a delusion about to racing my son up hills!
The non map displays can be extensively configured, I have a couple with most of the data displayed, and one with just three rows (Speed, Cadence, Heart Rate) that I can read without my glasses. I use an extened mount on the whizzy bike, so the unit sits in front of the stem/bar clamp bolts, the included band-on plastic mounts are fine on the Thorn stem.
The only other niggle I can think of is the HRM and Cadence sensors occasionally double readings, I can't actually pedal at 240rpm, nor can my heart manage 225+BPM ;-)
I'm not sure how well this will work but this Sunday's figures are here: http://connect.garmin.com/activity/386391477
This was a 'social' ride so I was not really 'going for it' ... honest!
hope that helps
sdg.
