I am going to reflash-probably over this weekend sometime. I've only had my n900 about a month. There's no problems with shutting itself down or being overly slow or anything like that. Battery seems to be OK too. As long as I tell it not to connect to wifi or 3g internet then I can take it to work and the battery level is still near the top when I get home. Using it a lot, surfing over wifi etc drains the battery a lot quicker ( which you'd obviously expect) and it wont last half a day when I leave it on like that.
The reason I am going to do it is because I've installed a few things from the devel and testing repos and there's 2 or 3 that seem to be a bit funny. When you un-install them the icons do not dissapear from the apps list, and stray files seem to be hiding all over the place. I am sure there must be some in the rootfs as well, because I am sure that there is less space returned when the apps are uninstaslled, compared to where it was before they were installed, I've also been learning the xterminal and I think I might have made a few things manual instead of automatic, which I think means they wont update automatically now. Certain apps wont load for me either when other people seem to be having a great time with them. It's not a huge problem. It mostly gets used for web surfing etc, but I'd like to be able to do the same things everyone else can and don't get why something works for one person and wont work for another.
So, that's the reason- Maemo is completely new to me (until I got my n900) and I have been on a very steep learning curve, so now I just want to put everything back the way it was when I got the device and create backup/restore points before doing anything with it again. I'll also be able to test the reported battery thing. It'd certainly be a nice bonus if it lasted longer.

Could someone just confirm( preferably someone who has done it already), that be reflashing the n900 will return to the point like where I took it out of the box? - same programs installed/not installed and all that? I don't want to flash the hard drive area, just the root area ( which I believe you can do) and I have found the guide on how to do it. It even looks like I can re-install the apps I want very easily. I just want to put my mind at ease that it does work like I think it does before I go ahead and do it really.