I think I understand you to mean that integral ribs are rare? I don't know which is the bigger job - fitting a separate rib, with all the fuss and mess, or having the equipment and skills to machine an integral rib. I suppose much would depend on your shop's capabilities. Lots of small one and two man German shops, handy with files and comfortable with traditional methods, might make soldering a better fit for them. Rigby/Holland or Niedner or G&H with more space, money, expertise and modern equipment, integral might be the way to go.
