Our pole downhaul and furling lines run through/inside our handrails the entire length of the coachroof without issue so I seriously doubt the tubing is introducing significant friction into this setup.
Mark has previously suggested that I'm overstating the friction issue and you may both be correct. Nontheless it's the curve that concerns me in that regard. All the pressure on the sheet as it goes through the tube is down which is why I thought it might be an issue.
The thing that jumps out to me is the lousy lead from the cleating block to the winch. Are you getting overrides there? I would think so. Good thing the cleated block is there so you'd have a chance to clear those overrides.
We find that a problem only when sheeting in a lot of line, say going from broad reach to close hauled. We seem to have gotten around that by only throwing one turn on the winch until fine trimming is required. Have to acknowledge that is not optimum.
Traveller adjustment cleats at the track ends? (pic is not clear here) That looks awkward too, but obviously leading anything down that arch is problematic.
Pain in the butt. We mainly sail two handed (three if you count AP) so when on any passage where one of us might be off watch the traveller adjustment is pretty much ignored until everything else is settled. Whatever happens with the mainsheet setup those lines are going to be brought down to cleats on the coaming somewhere. If we went German I could use the SS tube to lead the traveller controls to the cockpit duplicating the setup to port as you suggest below. Duplicating the SS tube on port side would not be difficult.
I would favour a double-ended German setup with stoppers either side. It would allow you to free either winch at any time, and give you mainsheet adjustability from both sides of the cockpit. Put the stoppers on deck level and the lead to your winches is improved too. Maintaining winch power should negate a need for more parts in the tackle. (good news/bad news on that idea.. the good: short throw to the boom so the 'added line' will be minimal, bad news: short throw to the boom may mean a bit of a cluster/jumble in the tackle when close hauled) Longer winch handles will help here too if not already using them (provided you can swing them fully past all your cockpit structures) This idea also avoids having to run your mainsheet through/under/around your windscreen to the dubious location on the cabintop (far from the helm, I imagine.)
Yes to long winch handles. Anderson winches come with their very own ultra swish monogrammed handles which is all very well and good but they are quite frankly less than wonderful to use. We only keep them for halyard adjustment and the like while we use those marvelous Lewmar One Touch handles (10") for sheets. I stress (as per my PM) that we never sail with that cockpit enclosure in place. It's a great design in that it can be folded away in seconds but in place it makes sheeting a nightmare. To be frank I also find it horridly claustrophobic when under sail and the only time you really want it is when the wind is so high that it would be a hazard to leave up. To be honest I even fold it away when motoring. If it is really cold but good visibility then I'll steer using the AP while snug and warm under the dodger, if poor visibility then one needs to accept the discomfort and stay at the helm so I can get a better look out. Of course in those conditions I've been know to pass the helm to the Wombet, go below and make a cup of tea.
Cluster jumble is of course an issue as it is on most sailing boats it seems.
I don't suppose you have that guide tube either side? If you went with German system, you could re-purpose the tubes and locking cleat for the traveler control lines... .
btw ... we do need to get decent stopper(s) on the coaming as I need to free up both pairs of winches for headsails. Off the wind we can gain an extra bit of oomph by deploying both inner and outer headsails though admittedly this is somewhat an illusory benefit. Below, say 15 we can use the assy while above 20 one headsail is quite adequate.