I believe we did have one customer who migrated from perpetual to subscription during the ""promo"" days and it was a 3-year agreement. There were no issues accomplishing that. It seems like someone at Sage at some point probably calculated that it was to their advantage to get the 3 years up front rather than be concerned about the annual increase. There is always that risk that they will get frustrated after a year and do something else, so that is a factor.
I am working on a few deals to go the 3-year Dimension Funding route, which would include the Sage subscription, third party software with 3 years of maintenance, hosting for 3 years, implementation and support/consulting for 3 years. For any configurations over 5-10 users, that becomes a big number, but they can pay monthly and in 3 years renew at a somewhat lower amount, since the implementation has been completed. The wild card in the formula is always going to be Sage cooperating.