Hi Chris,
Sorry to say I too have tried to find a problem with the Garmin maps and failed. No matter what combination of tile crossings, it always seems to do the right thing. I probably tried 20-30 combinations of routes across various tile borders. Is that a big enough sample size to see the problem or shall I keep trying?
No, along with AS's report I think that it's fairly conclusive that the Garmin maps don't suffer from this problem. So either they are providing extra info, or the info we are providing (and cgpsmapper too) is duff in some way. I haven't the faintest clue what could be the issue here so until we get some hint as to what the problem could be, I'm ignoring it. I simply don't have spare time to dream up possible reasons why this problem exists. Cheers, Mark