About 40 years ago, well before I needed glasses, I bought the Optivisor with #4 marked in a corner. Worked extremely well for close up details, but didn't need them often.
Then, at age 45, I suddenly realized that print and model details had become much smaller. (:>) So I went with gradually stronger reading glasses, finding them to be almost as useful as the original strength Optivisor, at last check I could double up the readers if needed, combination of 2.75 and 3.75 worked great.
Now if working really close I can use the 2.75 correction readers, combined with the new #7 Optivisor, looks awful but effective. Like the others, if you can find a reader set from the El Cheapo store, (where I bought mine,) I'd surely recommend that over the Optivisor. $1-$5 is a lot better than the $60 plus Optivisor. It the readers work for you, great, otherwise try the HF model.
The only thing really measurable in effectivenss, is the clearly superior optical quality of the Optivisor. They are really good, but don't buy them unless you find them to be notably better.
This hobby shouldn't break the piggy bank.