Can you describe a little bit more about this module? Perhaps provide a link to the WHMCS one you are referring to?
We evaluated Ubersmith and HostBillApp as a replacement for our current setup (custom orders forms that backend via SQL to WHMCS v3 with Kayako and Cerberus .. ugh what a mess) as a replacement and ended up going with Blesta (slowly making transition). While Ubersmith is very with modularizing the order forms, the price point did not make sense to us (the cost would be the same to hire a developer vs Ubersmith). HostBillApp also suffered from this, plus the lack of support (unless you call pay per ticket ... support).
If you could describe a little bit more as to what being worked in, I think it would interests a lot of folks here. Making the plugin/module free to use and opening sourcing it would be great for the long term (maintainability, feature inclusion, etc.)
Keep us up to date,
-Adam