I do have a .40S&W to 9mm Lone Wolf conversion barrel for my G35. It's a "drop-in" barrel so no extra cosmetics need to be done, besides picking up a G17 9mm magazine.
When I first shot it at the range, 100 rounds of Winchester White Box 9mm, I had some jams of failure to eject and stove pipes every other shot I took. I contacted JR at Lone Wolf and he said to try +P ammo or a lighter recoil spring (even though the G35 spring is the same as a G34 spring. I think I'm the 1% of having issues with this barrel. But the majority of others enjoy theirs.
I just picked up 250 rounds of Remington UMC 9mm and I'll have to use it up. Maybe the barrel needs to be "broken in".
Here it is:
Go try it out yourself. They are pretty affordable.