When you are using this folder, considering that you have a Trek 520 touring bike, you have the extremes, an ultra portable bike and a long distance load carrier. That gives you an opportunity to figure out what your priorities are in a folder for doing field work.

Lots of folders could be easily loaded onto a small boat. Some of the bigger folders would not be convenient to carry into passenger area on a ferry where smaller ones might be.

And some of the folders would be easy to pack for airline travel while others would be similar to packing a full size bike.

My point is that there is a huge range of folders out there, but once you use one for a bit, if you are unhappy with it, you will have a much better idea of what you really want in a folder.

While you are in the UK, if you decide to buy a bike locally there, make sure that they can help you get the VAT refunded as soon as you leave the country. And if you bought a new bike there and used it some, then brought a used bike back from the UK that you bought there, being used instead of new would reduce the value for purposes of paying any customs duty upon arrival here.