You're missing the ability to upgrade to the latest
software. The ability to switch between dual mode and
sensored only mode, the ability to adjust timing in both
modes, and setup custom voltage cut offs.
It's truly worth the $35. You will get all the software
updates for free. It's like a membership to Tekin's support
channels. It works on ALL the current Tekin speedos.
Regards,
This was my email reply from tekin.
Also, check
this thread out. Pretty much everything you need to know.
--pakk