I was ready to switch.
Wanting to break my TTM slump, I thought about going to ALL handwritten letters.
I haven't yet.
Why? I think it depends on who's getting your letter. Is it someone with bad eyesight who'll wince at my penmanship? The late Bob Will, a Cub who became a bank executive, said that typed letters were easier to read.
However, reluctant signers might suspect that you know the magic powers of a computer. To them, the lack of handwriting signifies that you're running a 24/7 operation, mass-producing autograph requests. In fact, whether it's a current or former player, someone who's never typed might think you're being lazy and impersonal by bypassing handwritten correspondence.
The only fact I'm convinced of is this: write the envelope by hand. I seem to remember from years ago that Jack Smalling tried offering pre-addressed labels from his baseball address list for a fee. I liked the temptation of speed, but knew the impression wouldn't be favorable.
A hand-addressed envelope is a good first impression. Once the envelope is opened, you've got a real chance, even if you used crayon.
Readers: do you use handwritten or typed? Why?