Symbolic Composer

I have it but I use it very rarely, to be honest.

Synfire shares some conceptual ideas with Symbolic composer (SCOM) such as the parameter concept, the separation of symbols and rhythm and the possibility to build up container structures. So, if one has mastered the concept of Synfire it can also help at using SCOM (or vice versa). But if someone complains about the steep learning curve with Synfire, he has not yet worked with SCOM. SCOM has no graphical UI and entering everything in LISP is really not much fun. And it's quite time consuming. Yes, SCOM has a lot of algorithmic phrase generation features too, which could be used as idea tools. But it's quite difficult to get anything useful from them. 

There are some other algorithmic phrase generating tools which come with a graphical UI, such as ArtSong or LMusix. For me it's more fun to use something like that. But also with those tools one should not expect to get phenomenal musical inspirations. They are nice tools to play around with when you are bored, no more, no less.

SCom is a very comprehensive "lab" style environment for algorithmic music. I used it in the 1990's already. For me as a software engineer, LISP was not an issue and I got some nice results.

Compared to Synfire, it takes longer to get some music going that also appeals to an average listener. Fractal, DNA and other algorithmic music can be very enjoyable if you understand and appreciate the concept. An unsuspecting audience however will probably not value it the same way.

Today, if I had the time, I would probably use it to generate fast moving textures. Stuff you can hardly play on the keyboard. And import these as MIDi files. Why not.