I use a 17C for my unlimited gun. I personally like it better than the long slides (34's or 17L's), but I will admit I haven't tried any after market ported barrels. My setup is a 17C with a little trigger work, a brass magwell, an extended mag release, a modified Carver Hunter Model Mount (more on that later) with a C-More sight, and a modified CR-Speed holster (for IPSC shooting). The modification I made to the mount was to move the top plate back by two holes, new holes were drilled and tapped to mount the top plate. This moved the top plate from directly over the ports to behind the ports. This solved a problem of getting splattered in the face by the stuff leaving the ports and hitting the mount. It also has the advantage of moving the sight toward the back of the gun. I think this modification works best with the Hunter model, because there are no ejection problems anyway. If you are using the competition model mount with a lowered port I'm not sure if you could get the same results. Again I love this setup, I think the 17C is a great shooting gun, plus if you are just starting in Unlimited I would seriously consider going with the Hunter model mount. You will not need to lower your ejection port or make any modifications to your gun. Also, with the hunter mount you can experiment with other slides because you can pop them right on with out removing sights etc. I even use mine with a 22 conversion kit for practice. Hope this helped, Jerry H
If you use the Competition mount for C-more or Aimpoint you'll need to lower the ejection port. In your particular case I think the Hunter mount is your best choice. I personally go with a non-ported barrel and a light load. If you don't reload or know a friend who does, do you have any friends who reload , then full power (factory) with the ports might work for you.
Here is a 34 with the Carver Hunter mount, sits a little higher, did not have to lower the ejection port.