I too feel very deceived by Coradine foisting this upon their customers, knowing that we don't really have any options to go elsewhere as it is very hard to export data accurately and easily.
I would pay upgrade fees for new features that I really need. But the risk with their subscription model is that Coradine will simply stop all development since they will no longer have any incentive to add new features once customers are locked into Logten Pro X.
I have written to them to clarify whether they are going to fix iCloud sync for existing LogTen Pro users - but rather tellingly they have not replied. I fear that existing users may be stuck with crippleware in order to try to force us to upgrade to their subscription model.