The convenience of the aluminuum toerails is an advantage. You can attach snatch blocks, bungee cords, tie
fenders, etc anywhere along the length of the boat you like.
Fitting them to a boat aftermarket style could be difficult. It's often very hard to get at all of the underdeck areas once a boat has been assembled. The presence of absence of liners and other finishing methods may make it virtually impossible to access all the necessary bolts to properly complete the fastening.
Nice that you can find 34' lengths - doing it in one piece makes for much more satisfying results. Not sure, though, how easy they would be to bend to the proper curvature - could require some simple jigs to get it right.
You also have the choice of whether to install them with the vertical flange outboard or inboard - I think putting the base flat outboard slightly discourages "streaking" from deck water running through the holes in the rail and overboard. If you can drain the water another way that's better too.
It would probably be a good mod - but not cheap - and, as SD points out, is it really necessary?