Upgrade for MC5 to MC6?

Is there any compelling reason to move from MC5 to MC6? MC6 is on sale for $20 at the moment. Honestly I use only a fraction of the features of MC5 as it is, mainly just a VST host and MIDI sequencer for me.

I'm still on SONAR Home Studio 6. I have MC 6 (and MC 2003 and MC Pro 24) but still use SHS 6.
If you think you may someday upgrade to one of the SONAR X1 programs, it might be worth getting MC 6 for $20 to start learning the interface and how the newer programs work. They're quite a bit different than the older programs.
I would either A. put the money away, saving up for an X1 purchase, or 2. put the $20 in the gas tank.

There ya go..... I stayed with MC4 for the better part of 3 years.... nothing wrong with staying with something you know and what works.

I don't know if you can call it an upgrade going from one version to a different version of the same program. Maybe an update, though.
I upgraded from MC 2003 to MC Pro 24, but Pro 24 had significant differences from 2003, such as support for VSTs (if you bought Cakewalk's VST adapter), 24-bit compatibility and 4-input recording instead of just 2-input recording.
If you want to upgrade, you should get consider one of the X1 programs. They include more synths, effects and processes than MC and the ability to record more than 2 simultaneous inputs.
But, at the price MC 6 is going for now, it might be worth it just for the Sound Center and Studio Instrument Drums soft synths.
I have MC 6 but still use SONAR Home Studio 6 because there are things it does that I use often which MC 6 doesn't do. I especially like using keyboard shortcuts while in Staff view. MC 6 doesn't have as many of those shortcuts, or I haven't discovered how to enable them, yet.