Let's get some things set first:

1. You do have your pitch bend controller set for only 2 semitones up/down correct? Anything more than this and you are going to have serious problems because it's pretty hard and uncommon for string bending with fingers to go more than that. David Gilmour will bend farther than that

2. most people that can do realistic guitar bends on keyboards are fairly accomplished electric guitar players. It's kind of a second nature thing and takes some time to get close to making it sound right. Why? Pitch bending a string is not a linear thing from a force/pitch bend stand point. The last bit of bend takes A LOT of force compared to the onset. This is one of those things that you learn by doing and doing and doing and doing.

3. I find that I simply cannot do a guitar-like pitch bend with a joystick. I have to have a pitch bend wheel. This has kept me out of the Roland and Korg markets for a very long time. Roland, in the past couple of years has put pitch bend and mod wheels on at least one model. What is your control, wheel or stick?

4. Even though you set your pitch bend range for 2 semitones, a whole bunch of guitar note bends don't go all that way, and it's the approach to the full 2 where the magic is.

5. A bunch of guitar bending is the somewhat seamless transition from bend to vibrato, another reason I find it almost impossible to do with a joystick, particularly Roland sticks which have so little travel in the vertical axis and it's hard to maintain a steady bend and add vibrato to it with such limited travel.

Here's one I just recorded on a synth patch that is the default patch in my Casio XW-P1. If I can figure out how to export the midi, I can try to send it to you. You'll hear and see that alot of the bends are less than 2 semitones and in between 1 and 2 and sometimes not even one semitone.

https://soundcloud.com/rockstar_not/pitch-bend-example

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