Sorry, I'm a little slow today...was on the ale all day yesterday. :? I thought it was you writing "I’ve pretty much got it figured out and operating the way I want it to, so feel free to ask me some questions." , but now realise it is part of the text from bikepacking.net.

My GPS will record total time (i.e. as soon as the unit is turned on) and moving time, which should be obvious what that does. As far as replacing a bike computer is concerned, if you want to look at it at the end of the week/month/year to see how many miles you've done, then I don't think GPS is designed for that (at least not as a stand alone unit). If you want to know how much climbing, distance, speed, average speed, total time, moving time and so on from a specific ride, then a Garmin will do just that. If you're downloading your data into Garmin software, it will aggregate ride distances for you over user-specified periods etc, but if you don't then you'll have to make an effort to record those ride stats elsewhere as once the unit it cleared of it's data then it'll be lost.

Sorry Ian, I should have made it clearer...my "bike computer" is a Garmin Edge 605. I was referring to the way the trip computer works on it. It was designed for biking though and some of my concerns with the Etrex are because it isn't. The things that interest me most in the Etrex are the longer life/replaceable batteries and the OS mapping. Maybe I should just get a travel battery charger for the Edge?

I have a Garmin edge 800 with the OS maps, I would recommend it but I don't have other units to compare it to. It is heavily training centric which is what the geek in me loves. DCRainmaker review is what convinced me.

I am not sure what battery life would be like for multidayers as I haven't tested it but have thought about the garmin power monkey thing for extending life.

During the 5 days i was riding in wales including Ians Orme to Gower ride I used my edge 800 every day. It was a simple and quite quick charge with my little two AA battery pack each night with lithium batteries.

if you do mess up and it loses power I have driven the unit direct with 2 rechargable 2800mAh batteries for 5 hours before.

S8tannorm - I know you already know about the Field and Trek sale this weekend...but did you know they also have the new Etrex's? £46 of an Etrex30! I'm very torn as I could do with a new camera first but don't know if I can pass it up with that discount?!? I need a camera for my Xmas holiday but won't need a GPS for it. :?

D45yth ... yes I'd seen that they have the new eTrex models. I had a look at the 20 which I could get for about £145 this weekend, however I'm under strict instruction that I can't buy anything from Nov 1st til Dec 25th

Trying to research the best way to be able to use my Garmin Edge 800 over many days...

Came across Portapow who sell a premium battery pack - anybody have experience of using this ?

Also there is a post from Numplunz ? who uses Edge 800:
"It was a simple and quite quick charge with my little two AA battery pack each night with lithium batteries"

Can you be more specific about the set up in order to do this ?

I use a variant of this to charge my Edge/IPhone.
http://www.amazon.co.uk/gp/aw/d/B004CHMP50

Using AA batteries with something like this?:
http://www.amazon.co.uk/gp/aw/d/B005NN6YPO