Well, I have an SB13 and a 19" LeBlond. I have five die heads. I used them once like 13 years ago on the SB in the tailstock just to try them out, and haven't touched them since. My biggest is a 9/16 D head, set up with 1/2-28 chasers, all the others are 5/16. They are a work of art, but if I'm only cutting a few threads here and there, I can have the threads single pointed by the time I remember where I put the heads.
ETA: I skim read your question then answered a totally different question. The only lathe I tested the 5/16 die heads on was the SB, heads in the tailstock in a Jacobs chuck (they are all 5/8" shank) and tried 1/4-20 down to 2-56. It pulled the tailstock just fine, especially if you have a tiny start turned down..
In general, if you can slide the TS without much effort, they work fine.