The HRC card will not run with a standard harness. You must use an HRC harness, or splice the stock one.
If you splice a stock harness, both the HRC and standard card will work, but they run very differently, so it's not a simple case of use whichever one you want. The jetting requirements tend to be significantly different between STD and HRC.
Splicing the harness retains lights and indicators [turn signals] but disables some of the warning lights and side-stand switch. No-one I know of can confirm if splicing the harness effects the operation of the solenoid on the oil pump.
So that's probably where the confusion lies. With an OEM spliced harness, you can run either card. The speedo [odometer] works with the STD card, but converts to a temperature gauge when the HRC card is inserted. The head/tail/brake lights work with either card.
As for whether it's worth it? Only you can decide. If you're happy to have a pin sharp 250 2-stroke neutered to around 2/3 of its power potential at the rear wheel, then run a standard card! However, if a concours bike is your goal, then you don't want to be cutting into an expensive wiring harness.
Ride an NSR250 with 60hp once though, and you won't want 40hp again!
(I'd never even want 60hp again! 
) _________________
Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
Check us out on Facebook! Please "like" our page!