I think the advantage of not having dirty wheels mark the walls is negated by the fact that the wheels are likely to dirty you every time you walk past, I reckon you'd end up scratching the walls with the handlebars as well, you're not going to be able to offer the bars up perfectly flush every time
I have found with bike hooks that you can have several in a row [as I do] and 'top and tail' your bikes alternating front and back wheels on the hooks which creates a more compact solution, you wouldn't be able to do that with a bar mounted design
not pissing on your chips or owt, just observations
I think the advantage of not having dirty wheels mark the walls is negated by the fact that the wheels are likely to dirty you every time you walk past, I reckon you'd end up scratching the walls with the handlebars as well, you're not going to be able to offer the bars up perfectly flush every time
I have found with bike hooks that you can have several in a row [as I do] and 'top and tail' your bikes alternating front and back wheels on the hooks which creates a more compact solution, you wouldn't be able to do that with a bar mounted design
not pissing on your chips or owt, just observations