Bending on the chromatic uses the same techniques as on diatonic, but requires more finesse in starting the bend and more fortitude in sustaining it.
Both blow and draw notes bend on chromatics, and often by two semitones or more. However in the top octave typically only the draw notes bend.
Many modern chromatics bend just fine out of the box. Stevie has always used customized chromatics, originally by Frank Huang when the Huang brothers worked for Hohner, later by others.
Two things affect bendability: airtightness (more is better) and reed gapping.
When you bend a note down, it draws the reed tip closer and closer to the reedplate. At a certain point, the reed can no longer emerge from the plate to complete "chopping" action on the airstream - it gets stalled in the slot. At that point the note blanks out. By raising the gaps slightly you can increase the bending range, but you have to be careful not to make the reed unresponsive to gentle attacks.
Here's Jerry Murad of the Harmonicats bending a C down to about an A on Cherry Pink and Apple Blossom White (played in F):
And here's me doing the same thing, but playing it in C and bending down a G on two different chromatics (I no longer remember which ones; this was about two years ago when a similar topic came up somewhere):
Regarding bending notes on the chromatic, are we playing be the same rules as on a diatonic harp, i.e., we can not bend the pitch down to that of the other reed in that hole? If you're bending lower than the pitch of the other note, a different process must be happening.
Chromatics are not subject to the same pitch limits as diatonics. Valves prevent the blow reed and draw reed from interacting except in the top three holes, which are typically unvalved.
A valve (or windsaver) is a strip of flexible plastic (or, in olden times, leather) mounted over a reed slot on the opposite side from the reed.
When you inhale, the valve on the outside of the plate, mounted over the blow reed, gets pulled shut, preventing any of the inhaled air from coming through the blow reed, and preventing the blow reed from any involvement in the draw note - and the draw bend.
When you exhale, the valve on the inside of the plate, mounted over the draw reed, gets pushed shut, preventing any of the exhaled air from going through the draw reed, and preventing the draw reed from any involvement in the blow note - and the blow bend.
This removes the limits to bending range imposed by a responder reed, which is why half-valving a chromatic will severely limit the range of its draw bends.
On the other hand, you also lose the good qualities of dual reed bends - the vibrant tone color, the ability to start a bend with a strong attack, and the ease of sustaining a bend and holding it at pitch.
Since bending the notes on a chromatic harmonica are more limited, thanks to the 'good old valve/windsaver', why not try going with a Seldel Standard 12 hole chromatic, or even the Swan 1040 chromatic. Both models don't have windsavers, so bends can be accomplished more easily.
Valves make bends LESS limited, not more. I already posted recorded examples that demonstrate this fact. You can bend FARTHER on a valved instrument.
Having no windsavers at all weakens tone and volume, and makes chromatics extremely leaky. And it will limit bending severely.
With full valving, all blow notes and all draw notes will bend down at least a semitone and some as much as three semitones.
With no valves, you'll never get more than a few one-semitone bends and a couple of microtonal bends. For instance, in the first octave, Draw 1 and 3 will bend down a semitone, while Draw 2 and Blow 4 will bend down a quarter-tone. Even when you double those for slide-out and slide-in versions, you still have a pretty meager set of scrawny bends.