It'd prevent me using the Vim clipboard ('registers') between files. That's bad enough. It'd also prevent me using Vim macros to easily shuttle data between files.
I may also want to ctrl-z Vim to run a few quick commands before resuming Vim with fg. Using tmux panes, I'd only get a small window to run those few commands, which doesn't reflect my intent. (Yes, I could use another tmux window for this, but I like this way.)
Amp has native clipboard integration, so content will carry between different instances. Configuring the register => clipboard was something I personally disliked when configuring Vim.
Amp also supports suspending (hit "z" in normal mode) as I use that workflow all the time. As for the small window issue, you can "zoom" a tmux panel with <leader>-z. I get that this is less than ideal if you're used to the suspend action collapsing all panes by default (and expanding them on resume). Workflows are tricky; to each their own, I guess! :)
> Amp has native clipboard integration, so content will carry between different instances
By "native" does that mean an X-server's clipboard? So when you're running it on a machine that has no X-server running (a typical server), there is no clipboard?
Amp has an internal clipboard that it synchronizes to an external/native equivalent, if available. You'd still be able to copy/paste within a single Amp process, but you would lose the ability to do the same between separate processes.
Right, so in the context of this discussion, tmux panes are not a good substitute for vim windows, since you wouldn't be able to copy-paste between them unless what you were copying fit in a single pane-full.