HI I have a few 1980's road bikes with the threaded aka quill stems. I have discovered that Nitto Technomic 100mm stem works perfect for me. I have 1 already. Remainder of my bikes have either shorter orig. type stems or some old hybrid adjustable stem that my LBS found for, but dont fit me as well or look as nice as the Nitto Technomic stem.

So I am considering buying some more Nitto Technomic stems. What i dont like about them is that if i want to change out the handlebars (ie if i find ones with a better fit, ie I like 42mm but most of my bikes have 38mm becuase it was more common on old road bikes, and one of my bikes has handlebars that have more of a reach front to back than i like) later, you have to undo the bar tape. I am still experimenting/swapping out handlebars bike to bike (ie some of my old bike have 38mm handlebars and I prefer 42mm and also one of my bike has handlebars that have more of a reach front to back than I like. Also i might want to try other types of handlbars like randonneur or moustache etc.

So alternatively I am thinking of getting those items that convert quill stem to threadless stem.
The benefit of this to me is that i can then use modern stems and if and when i want to swap out handlbars it is a lot easier-- you dont have to remove tape from the bars to swap them out with modern stems.

But i am concerned with these conversion products i will not be able to get the same amount of stem height, and not close to it, as i can with the Nitto Technomic stems. I am pretty sure I won't so i am planning to go ahead and buy some more Nitto Technomic stems but i thought i would ask first on here to see if my assumption is correct.

Another advantage of the Technomic is I feel it is safer beause the stem is 1 piece. With that conversion piece then a modern stem, there is more of a risk of the screws getting loose which could be catastrophic if it happens on a ride or during a crash. I have already had the experience of a hybrid adjustable stem getting loose on a downhill which is one reason i dont want to use that sort of stem anymore.

On the other another advantage of modern threadless stems is you can swap out just the stems to change length to/from without having to retape the handlebars but i find 100m works for me on my bikes so far.