[Chris is me]

As a counterargument, our two wheeled linear shooter had plenty of shot consistency with a smooth polycarbonate wall on the opposite side. Our shooter was far from an optimized solution, but if you're trying to build a simple cycler, you don't need a perfectly optimized solution. You just need a consistent and effective solution.

Here's our shooter specs, if it helps you:
- Two Banebots 4 7/8" wheels plugged into two mini cims or a cim + mini-cim (honestly doesn't matter) using the AndyMark 8mm to hex adapters
- 10.5" between the tips of the wheels and the opposite wall of the shooter (so .5" disc compression)
- Polycarbonate on the opposite side of the shooter. I've heard from MANY teams that wedgetop tread or other grippy material works well, so consider that an option too, but you might not need it.
- Plastic strips above and / or below the shooter barrel such that frisbees sliding through are physically constrained in the shooter. Basically what this does is it forces the frisbee to contact both wheels rather than lifting up between the wheels and not getting full contact. This dramatically improves vertical consistency.

We used an aimable shooter so I can't tell you if this consistently fires the exact same height over 1,000 shots, but if everything was working all 4 discs would hit almost the exact same place every cycle. This definitely isn't the best way to build a shooter, but "done" is better than "perfect".