I am about to perform an upgrade of AXP 5.6 to MC 2.8 and was wondering will I face any issue with opening the old AXP projects in MC?

Well, I didn't when I did the upgrade.  And I'm still having no issues with MC 3.0.  In fact my leader and test signal stock project was first created in xPress DV 4.5.something, and is still being used.

 3.0 supports all previous Avid resolutions even back to AVBV days, but most of the legacy resolutions are read only.

Baja, Avid projects tend to be very compatible between software revisions. I've brought back and forth projects between various flavors in the past without any issues. Used to take projects and bins from MC12 to AXP4.8, from MC7 to MC9/10/11, and from SN 1.7 to AXP 5.7, and from MCA 2.x to AXP 4.8 and from MCA2.x to MC11/12. Never had any problems.

If you want to guarantee success with the changeover, don't use the old projects. Create new projects in Media Composer, then exit, and at the desktop (files) level, copy or drag your bins from the old projects into the new ones. There is no question that the bins themselves will be compatible. It's an easy and trouble-free solution.

Ted

That's the most reliable way to do it, but I've never had problems opening old projects.  The thing to bear in mind (and I'm sorry if this is too obvious) is that your new project name should be identical to the old one, otherwise your media will remain associated with the old project.

 One caveat about going back into Meridien based projects. Any SDII audio files will need to be converted - say to AIFF-C, as support for SDII was dropped in the transition from Meridien to Adrenaline.