Hi Jakk,
You are still an Aras subscriber; you're just getting your subscription through one of our partners (Infor), so you should still have access to managed upgrades through Aras.
In general, the complexity of an upgrade is tied with how customized your instance is. If you have a lot of custom methods and events, an upgrade is going to take longer and be more involved. Between service packs, the API may change which can require rewriting existing methods so that you don't lose functionality. For very customized environments, it may make sense to do your upgrades in several jumps to minimize the scope of what you need to rewrite each time. The end result is the same regardless of if you do one big upgrade or several smaller upgrades.
Chris
Christopher Gillis
Aras Labs Software Engineer