Oz,
They basically did what you were saying... as I have read here, anyone who has purchased an extension in the last 30 days can have that money applied towards the subscription... I am sure they would be willing to carry that on... where someone could try out dataAssist, for example, decide they love WebAssist stuff and then could call sales and instead have their purchase applied to the subscription instead. While I don't want to speak for WebAssist, this appears what they are doing right now.
Best regards,
Brian