Although a nice idea it's completely unrealistic to expect pilots flying VFR to use GPS as a backup to visual navigation the way that publications tell us that we should.
My interpretation of the 'proper' technique is that if you fly with a GPS it should only be used to confirm the integrity of any dead-reckoned position. With the airspace system the way it is in the UK and the ambiguity of compass and stopwatch navigation I can't imagine anyone actually doing this.
My opinion is that if you want to navigate primarily using headings and times it's best not to activate the route function in your GPS. All that will happen by having a line displayed on the screen is that you'll see that you're off-course and then turn towards the line, thus undermining all of your calculations and surrendering to the more instantaneous source of information.
If you want to navigate VFR using GPS as your primary method then that's fine. Have a line on a chart and record your fixes periodically in case the unit stops working and you have to revert to DR or feature tracking. Under normal circumstances however there should be no taboo in turning right if the GPS indicates that you're left of track and vice versa.