Hello,
I have both. I have retired the H and now exclusively use the H4.
More points to check a frequency range.
As far as requiring a metal case, I have compared my H in metal case, and the H4. The results are the same for both. Unless you are in a super noisy environment, a metal case is NOT really needed.
Myself, I would buy the H4 again. More features.
Clyde KC7BJE