coolhandluke-bloke:
Getting the right length is more important than stiffness imo.
That’s what I think as well. On my mountain bikes I like to “tune in” with the stems (length) until I’am really happy with the bike.
Means: fairly low cost stems. Recently RITCHEY.
Problems I had with bad designed stems: if the clamping to the fork-tube isn’t good the headset bearings loosen up. Adjusted the bearing play, torqued the stem to spec and after 2 weeks the bearings were loose again. This stem was too cheap…
Short stems and “flex”: doubt that somebody is able to feel the difference…