Bryce
I've had good results printing PC, PC alloy, and PC composite on the Nautilus.

I've tried:
  • Priline's Carbon Fiber filled Polycarbonate
  • Gizmodorks' Polycarbonate (blue)
  • 3DXTech's CarbonX Carbon Fiber PC

All were successfully printable on the Nautilus, which I will describe below.

Note 1: All prints were done with a warm chamber, that is, the chamber was allowed to achieve dynamic equilibrium with the heat bed running at the printing temperature. The X 400 toolhead was used for all prints.

Note 2: Some people may disagree with using ABS Juice on a PEI surface, which I did for one of these materials. PEI is reasonably resistant to acetone, especially when cold. However, PEI may also be embrittled by ketones, which might lead to degradation of powder coatings over time. Anecdotally, I have also heard that using acetone on PEI decreases its adhesion toward PLA and ABS/ASA. This is consistent with my own observations (I've been using PEI beds for several years), but cleaning it with alcohol seems to restore it, i.e. it is not a permanent effect. In any case, having occasionally used ABS juice on PEI for years, I've not noticed any problems, but I don't want to be blamed if something goes wrong with your particular PEI bed. Maybe try kapton tape under the ABS juice instead if this bothers you.

pc_gizmodorks.jpg 
Above is the toolhead frame from the Nautilus, printed in Gizmodorks PC.

Priline's Carbon Fiber filled Polycarbonate

First, I don't think this filament is entirely polycarbonate. It could be a modified PC or a polymer alloy with PC. Also, the carbon fibers in it are very short. That out of the way, this filament prints beautifully and seems to have a heat deflection temperature between ABS and PC. It is pretty strong. It is about as stiff as other PC, but not as stiff as I would expect from a filled material.

I used the Protopasta PC/ABS profile to print this without adjustment. I used the stock Nautilus PEI bed, wiped down with alcohol before printing. No brim was required, even with unfavorable geometries. No warping was appreciated. I printed out most of the parts for a Lulzbot Taz 6 toolhead and X carriage from this material, with no failures or significant defects. The surface finish is very aesthetically appealing. This filament prints fine with 150 micron layer height despite being a filled filament, which I suspect is because the fibers are so short.

Gizmodorks' Polycarbonate (blue)

I think this is real polycarbonate. It is not filled. The prints look good and are quite strong.

I used a modified Protopasta PC/ABS profile to print this, changing the extrusion temperature to 300C. I used the stock Nautilus PEI bed with ABS Juice. (Plain PEI wiped with alcohol failed.) I used a 5mm brim, but I don't think it was actually necessary; it may depend on part geometry as I have only done one part with this so far. No warping was appreciated printing out the Nautilus toolhead frame (depicted in the picture above.) I used 150 micron layers. There was excellent separation of the support material. Minor ringing artifact was appreciated. Bridging performance was good. Layer adhesion was great at 300C.

3DXTech's CarbonX Carbon Fiber PC
This is a carbon-fiber filled PC. It may be a modified PC.

I used a modified Protopasta PC/ABS profile to print this, changing the extrusion temperature to 300C. I used the stock Nautilus PEI bed, wiped down with alcohol before printing. I used a 5mm brim but I don't think it was necessary; it may depend on the part geometry as I have only done one part with this so far. No warping was appreciated printing out an E3 V6 extruder mount. I printed it with 200 micron layers, since it is a filled material.
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Bryce
As an update, I tried the alternative to using ABS juice on the bed that I suggested above - using kapton tape, with ABS juice on the kapton tape. This worked pretty well, though I noticed a very slight degree of warping on the part. It might be acceptable for many applications, it is a few % of the height of the object. (Same test object - the X 400 toolhead frame.) It might have also just been related to my imperfect kapton job. In any case, though, that appears to be an alternative that could be dialed in, for those who don't want to use ABS juice directly on a PEI bed.
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John Kray
Thanks for taking the time to share all your testing with PC. More support for PC is planned for future Cura plugin updates and this provides us with a little extra helpful data. 

@tinkerz though you might find this interesting
John
Founder/CEO of Hydra Research LLC, developers of the Nautilus 3D printer and providers of 3D printing services.
https://www.hydraresearch3d.com/
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