I always discard the initial water when I turn on the unit, and the DI Bypass valve is critical for this. Because of the TDS creep when the unit is off, this is a huge benefit in extending DI life. DI cartridges are $30 each, so this can make a difference, especially if you're hooking a float valve to your sump to have the unit turn on/off automatically.
I occasionally use the fast flush, although I'm not convinced it's critical. The RO only output is useful if you want to use the unit for drinking water as well.
You could probably purchase the parts for ~$25 and do it yourself, if you understand how it works and what needs to be done. You have to decide for yourself if you need/want these things, and what it's worth to have someone else do them for you.
Jeff