I think it's entirely reasonable to encourage current Sage customers to ""look at other options."" Most will decide that the switching costs aren't worth the modest, if that, decrease in ongoing fees with the alternative. IMO Most Sage customers who change are doing it for other reasons, with any cost secondary or tertiary.
Of course, helping a customer ""look at other options"" would be a paid engagement. Fixed price, not cheap, as it would involve applying your highest value as a consultant to addressing their problem which could return significant $$$ to the operation.