You are right, the JRE is included next to the Linux executable. Well, it is already a progress. Having to install Java was kind of cumbersome.
well I am happy to use Transmit for my FTP stuff… never have had problems for years…
I’ll throw in Flow, my favourite FTP client: http://fivedetails.com/flow/
Coda is mine 
Since others are suggesting their favorites, I will throw WebDrive in. Never had a problem with it and have been using it for 5+ years. http://southrivertech.com/products/webdrive/download/
FOUR years later
I can’t remember the last time I used FTP actually. I even wrote an FTP server in RealBasic once, but it’s been so long since I needed it for anything. Everything I transfer is either SCP or SMB now. SMB for GUI stuff in the finder (my own personal sites live on my NAS and I can just SMB to that), or SCP to a server somewhere on the command line. If I don’t want to type out a long path I just drag the file to the terminal window. It’s quick and simple and secure. I guess I still use AFP for time machine to the NAS, but that will probably change to SMB at some point once I’m brave enough to upgrade to Catalina.
I love these two Swiss products 
If you don’t want Dropbox, OneDrive, Google Drive to “sync” - just mount them, copy some files in there, edit some files, … and be done. No need to sync all, or setup what you want to sync to the local drive.
My (Synology) NAS is backing up to Microsoft Azure (Blob / Container Storage). If I want to explore the Backup, Mountain Duck lets me mount that storage location, and I can easily explore that “Cloud Storage” with Synlology’s GUI client (HyperBackup Explorer).
Never had any issues with CyberDuck/MountainDuck - so I can’t say one needs to be “careful” with those
This topic has been pointlessly re-woken.
My original message was simply about the compatibility of two specific versions of Mountain Duck and Cyberduck, as things stood 4 years ago.
It was resolved 4 years ago.
Yes, Mountain Duck is fine now, and the person who today pointlessly replied 'Mountain Duck works fine’ has even deleted the comment since!
Nothing to see here for 4 years. Use what you like. Nothing to solve.