Most chromati players who play in all keys stay pretty much with the C instrument. I use a G 270 occasionally for the range (i.e. violin low notes). I may get a Bb for easy draw bends where they are missing on the C. A D would accomplish the same thing. Richard Hayman likes A, also a popular key in harmonica band days.
If you know the 12 major keys on a chromatic, the key of the instrument is not much of a problem. Transposition just takes a little practice. I once noticed that the opera Carmen has 12 different transpositions for the French horn players. Professional horn, trumpet, clarinet, and sax players transpose all the time. Good Alto Sax players have no trouble reading C and Bb parts even though their instruments are pitched in Eb. Etc., etc.