I think you'll notice that a majority of the users that previously bought a license is using FTPRush with mirc dll.
So you probably need to rethink the "not supporting mirc very well" problem or just accept that all those users will be forced to look elsewhere for a client that suits their needs.
Its obvious you didn't foresee this since you removed the up/dn slots per site setting in the first free version,
overall it seems like you put alot of effort developing stuff that most of your previous users doesnt even want or will use, nothing wrong with that but as i said, if you have any ambition to keep you old v1.x users you shouldn't break any of the stuff related to fxp part.
But the way this is client is heading i guess its already too late for that.
I honestly don't know, maybe this is the best overall client now but for your old users you made it pretty much useless.
Still nice of you to offer 1.13 version indeed, but shame that we cant expect any more updates/bugfixes which was what we payed for in the first place.