Your problem is that the Chromatic Harmonica is a melody instrument, and a reed/wind instrument, at that--On guitar, you keep the rhythm and fudge the melody, but on harmonica (and reed/melody instruments in general) you play the melody and fudge the rhythm. The players conentrate on keeping those single notes clean and in perfect time--everything else comes after that.You have to deal with breath control, tongue technique(Beavis and Butthead would love to hear about this) timbre, and dynamics which are either completely new, or handled completely differently, and you have to deal with the concept that your phasing is controlled by your lung capacity--
The other problem is that the music that you play on the Chromatic Harmonica tends toward the written(which not a problem for people with classical musical training) The chromatic harmonica was the perfect instrument for music teachers way back in the days when lessons were cheap and real instruments were often unaffordable for kids--they could learn to read, play melody, and work with small ensembles, and it was an excellent foundation for other instruments.
My Dad used to play the Chromatic, though he hasn't picked it up in years. He was a "Old School" player, which meant no blues or Jazz, but a lot of the old time popular songs, sentimental songs, and of course, the novelty songs --as a result, I picked up a bit, though didn't necessarily appreciate it a the time--In fact, when I read the Larry Adler thread, I got out my old 64 Chromonica and played "The Spanish Cavalier", though I couldn't remember quite where the little chromatic descent fit in--
As to the pedal steel, there are only nine people in the world who can play it--