I have Tracklogs and I have a 305. Personally, I've gone off Tracklogs - there are too many minor bugs that don't get fixed. The only thing I really use it for is to get accurate elevation profiles for my runs. I find that the mapping used in SportTracks is adequate for most other purposes, and covers the whole country (and beyond).
Having said that, someone on another board mentioned that it is possible to create routes in Tracklogs and load them into the 305, so that it can be followed during a run. I've not yet investigated this but, if it is true, I might start making more use of it. I know that Tracklogs has the required functionality - it is just whether it is the case that the 305 has the functionality to import the route and then have it available for navigation.