Not there yet, but approaching what I'd like to use.
KXstudio on top of ubuntustudio 12.10 very much does the trick for me. I can either use Ardour 2, recording acoustic tracks only, maybe with the metronome, and leaving drum integration for whenever; or I can use MusE, which gives me internal MIDI instruments (something I'd like to use a little, even though I'm basically a guitar player without a MIDI guitar), and maybe (if I can get SimpleDrums, the internal percussion thingie, to work) even rhythm.
I'll want to use just one piece of software. Used MusE today and upon reentry the connection with ZynAppSubFX (or whatever it's called) was lost. I want to sit down an play if I can.
That said, it looks like the layer of integration provided by KXstudio is a good model. I read somewhere that Debian will have a saner sound infrastructure soonish. We might yet get to the point in which you can download an .iso image, burn it into a DVD, install it into your hard drive, and just use one piece of software for the basic frequent activities.
We've come a long way since, say, 27 years ago, when I used our Apple IIe to write 394 lines of assembly code (that's as close as machine language as you can normally get) which accepted keypresses on the numbers and returned a list of "note, duration" pairs.
I just want the flow I get from playing alone, then playing against my own previous track(s), then maybe redoing the pieces with greater care so as to show what I hear inside, and finally maybe even playing with others if they want to.
Not much of a request, I think.
And it does look like we, free software zealots/fans/enthusiasts, are getting there.