This request is actually being tracked already:
https://winscp.net/tracker/1502
You can vote for it there.

I think if I understand the original request right, that this is exactly what I've been trying to find out if it was possible to do...

As it is right now, we have a global setting for the maximum transfers at the same time. It defaults to 8, which for me as well has been perfectly fine. Until recently, when I gained a new client who's server does NOT like 8 connections at once.

Therefore I'd like to ask for two featurss:
1) The ability to set # of transfers on a per site basis, which if not set defaults to the global. This is I believe what the original poster was requesting.

2) When a server complains of two many connections, the dialog that pops up should have two additional option buttons:

A) Pause All Transfers
B) Cancel All Transfers
Otherwise it just get's stuck in a loop that you can't get out of unless you're quick enough to suspend or cancel all transfers using the right-mouse button menus.

Thanks.

Thanks for your suggestion.
We will see, if more people ask for this.

Currently the Background Transfer Limit, how much concurrent connections are allowed, rename on server or background transfer is set up globally. this works fine for most servers.
but connection to managed switches we need to push a file named /flash/primary
important is: no background transfer and 1 connection per whole session only,
to set this a setting per bookmark would be fine. the master setting as global but if defined it should be overwritten by bookmark.
another important thing is, that an upload has to be the same name as the target filename. rename operations are note permitted and chmod also not. this should be disabled too for these bookmarks