My mac is running macOS Sierra 10.12.1. I think my mono is installed correctly because it shows the version when I type the command into terminal. If it helps.. I was having a lot of problems with rocksmith itself recently. My mac wouldn't even open rocksmith at all for some reason. But now it works and the tool kit is giving me the "you need mono 2.8 or higher installed error."

 

"  Mono JIT compiler version 4.6.2 (mono-4.6.0-branch/ac9e222 Wed Dec 14 17:02:09 EST 2016)

Copyright © 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com

TLS:           normal

SIGSEGV:       altstack

Notification:  kqueue

Architecture:  x86

Disabled:      none

Misc:          softdebug 

LLVM:          yes(3.6.0svn-mono-master/8b1520c)

GC:            sgen

What version of the Toolkit are you using?  The latest versions have removed the mono check at startup.  However, the last two versions posted (Jan. 5 and Dec. 14) have other bugs that prevent them from working.

 

I use v2.7.1.0-8c786b1e with no issues.  No Mono check in that one either.

> However, the last two versions posted (Jan. 5 and Dec. 14) have other bugs that prevent them from working.

 

The second Dec 14th build and today's work for me, but no mac builds previous to those did

That's weird.  I get nothing but errors with the last two versions.  I can't even get past the initial setup screen without an error.  And I'm running the same OS and version of Mono as you.