[zomgwat]

It sounds like we've had very similar experiences. The fact that what you've described is so similar to what I've seen may say something. There are reasons to have a bespoke billing system but people should try REALLY hard to avoid the situation.

Something I saw regularly with one-off style sales deals was not accounting for the collateral damage to business processes like end-of-month accounting. It's not just the development costs for adding support to things like subscriptions. Changes ripple all the way through the business. Updates to the bespoke billing system (and related business processes) end up half-baked because they aren't a core part of the business. I've seen sales deals end up as a net loss over time due to the increased labor costs on the backend. Having some reasonable constraints that an off-the-shelf product will intrinsically enforce can prevent a lot of pain for all involved.

[mgkimsal]

It's never pain that the sales folks have to bear, it seems. :)

[zomgwat]

Ha. Nope.