It's not the migration credit, but also not really SLP. When they did the migrations, Sage was matching the previous Sage 100 maintenance, and in some cases there were negotiated amounts. Because of this, the SLP does not match what they paid and what +10% would equal, so I doubt this implies a standard price increase, which is only for new customers or module/user additions.
I told customers who upgraded that although the Subscription Order form stated at the end what the estimated renewal would be, they needed to note that it also stated in small print ""prices are subject to change."" I'm sure many did not read that and will forget, so we will have customers calling from now until the end of the year about this.