D Cook, I play klezmer on the melodica. You can play klezmer on pretty much any melodica, depending on the sound you’re looking for. I mainly use the Hammond 44 and Hammond 44 HP for this purpose, as well as a Suzuki Pro37V2 at times.
In general, I think the “warmer” sounding melodicas like the original Hammond 44 (not the HP) or perhaps something like the Yamaha P37D are “fuller” sounding choices, especially for solo/small group playing,but it really depends on the sound you’re going for and the band you’re playing with. I find the Hammond 44 HP often cuts through better when I play klezmer with my rock/ska/reggae/world fusion project.