I presently only have one bike with telescopic forks. either normal or upside down ones. I don’t ride much but my first Triumph had girders which I replaced with Matchless Teles. Its 64years since and I think it might have been an improvement. I did use to make F1 shock absorber parts , they were searching for improved damping in both directions,and adjustable at that. So whilst its quite obvious that hydraulic damping is superior to friction, it will depend on other things if handling is to also be considered. A pair of good Girders might well be better than some tubular based teles. I think that Vincent’s were girders with hydraulic damping. I can also possibly claim to have straightened more telescopic forks in York than the rest put together. Only repaired perhaps 10 girders of which the Scott which is neither was in its original brazing a bit suspect. My first Norton had girders , I was just glad to get it to run and it took me 10 miles to get it out of first gear !