Harvey maps were designed for the hiking/mountaineering market so it's obvious they've improved on OS maps for that use. It's why they use 40k scale. I use them too with copies for most lakes areas including the BMC versions for the Lakes and a few other areas too. I even have a few of those mini area maps too. I'm actually on my second BMC lakes map or possibly third, third it is because my second got left on my car roof and despite going back just couldn't find it again.
Btw as good as plastic maps from Harvey's are they do lose the print if you use them a lot. My two old copies lost a fair bit of the mapping and my current one isn't going to be good much longer. However I've got paper OS 25k maps of the lakes that has had longer use and still useable. Indeed there's a little bit of the folds tearing but it's perfectly useable. It's been soaked, dropped into a stream and used its whole life without a map case too. I only stopped using it because I got the plastic covered maps instead. Those leak eventually at the folds imho.
Yet to completely destroy a paper map but have worn a few plastic ones.
PS I often used to carry a few maps. Usually a Harvey's and a 25k OS. Now I mostly know where I'm walking and not doing so much. If I even carry a map it's only in my rucksack and possibly looked at for interest only to check something out. You tend to learn areas after you've been there a few times i find and maps are needed less with each visit.
