@impression
Sending the polyphonic note data directly to clone via send a receives to clone and receiving from the right node (rejected) of route in the synth works ok, So yes its possible.
testPage-updated.zip

give testSynthClone a unique argument $0-three
in testSynthClone put [r in-$1]
in testPD put
[ s in-$0-three]
|
[all cutoff $1(
|
[clone testSynth 4]

testPD.zip

You can prefix the number of the cloned synth in a message to that synth eg 2 cutoff $1 then within the cloned synth and route the cutoff value and pass it on polyphonically with all cutoff $1
clone-project.zip

Damn too late again

I've just updated the above poly-dynamic to pass through the clear and stop messages to poly

I never found a way to change the number of voices in the poly object other than changing the creation argument. eg [poly 8 1] to [poly 1 1]
Here is an abstraction to address this

poly-dynamic.zip updated

if you mean pitch shifting with constant duration
3.audio.examples/I07.phase.vocoder.pd explains how to do this:
The [pd read-windows] sub patch within [pd fft-analysis] sub patch explains it more
here is a sample recording from a project I'm currently making using this
puredata.mp3

Here is way to get a bit more out of the soundfont generators using NRPN to address them. I've had this info for a very long time and can't seem to find where it came from.
You will need to change the path to your soundfont in [else/sfont~] and use the sf2-presets-reader.pd to create soundfont.txt if you want to use choose-sf2.pd.
Probably not that useful, just a bit of fun

Edit: I found the source of this info in the soundfont 2.04 spec

sf2-toy.zip

I've just updated choose-sf2-example.pd in the zip in the original post because it was incorrectly wired and triggered, causing the previous index and current bank to be sent immediately before the current index and current bank often causing an error. I noticed it when I connected a print object to else/sfont~ right outlet
choose-sf2-example.pd

@porres I removed else from my startup preferences, declared -lib else in a patch and else/sfont~ now loads successfully