The steel braided brake line is slightly stiffer than standard rubber/fiber corded hose which came as standard equipment. Easy way to check right regular rubber brake hose: wrap your left hand around it, and squeeze the right lever with your right hand firm, feel the brake hose swell...now remember this is all along full length of rubber hose all the way down to the caliper, (simply fluid hydralics)...this is what contributes to the mushy feel. Do the same with a bike with steel braided hose and very little swell is felt, and the lever feels firmer.
As far as the foot operated rear, the pedal/lever/linkage flex contributes so much more to the mushiness than the rubber/fiber corded hose, so very little benefit is gained here. Matter of fact, Harley does not provide their Diamondback sheathed braided rear brake line probably because the benefit is so much less and more costly to make the combo formed metal and braided line used on my Sporty.
Since I use the rear brake less anyway, it just provide some stopping and helps equalize (level) the chassis attitude (dive during heavy braking) of only 30% of your braking in the rear, so I did not even bother replacing it. I can still mash down on the pedal in spite of the mushiness and induce a rear wheel skid, so feel or stopping power is not an issue.