Why not get both and try them. Your only blowing off a few bucks and what if you order the wrong ones?
If you stay with dowsing you will make, or have made for you, precision L rods. I used super slick bearings that I use to salvage out of Sony VTR decks. These are precision bearings that were in the tape idler system on $30,000 prefessional VCRs. There are other sources for such bearings. The bearings in the motor on computer hard drives come to mind. Look around!
There are professional L rods made with such bearings, and if you got a war pension you don't need, you can get one right away. In the mean time use coat hangers if you have to. All roads lead to Mule Shoe, Texas you know
Mitch