Cam Operating Range & Highway Driveability

If the advertised operating range is outside of highway cruising RPM, how does that effect driveability (I know that's a vague term)?

If the cam & intake are designed to operate between 3000-6500RPM and your gearing is set up to run 75 @ 2500 rpm, will the engine be dogish or struggling under these circumstances? Or does it just mean you need to drop a gear and mash it if you need power on tap?