Bryan, I second the comments by Georgesilverman and Bill46. We love our R31 and are glad we made the leap up to it from the R27 (which we also loved). Here are my more detailed thoughts in answer to your questions:
Maneuverability/dockability: The R31 is of course bigger overall (5' longer given the bigger swim step, plus 1.5' of added beam), so it needs more dock space. But despite the greater size, it seems equally maneuverable and more dockable. The added gross weight (nearly double the R27) is a big plus for docking. It holds course better and other forces (like wind and current) don't mess with it like the R27. The R31 is the first boat of its size that I have handled, and I now understand the advantages in docking. The thrusters on the R31 seem to have more "authority" than they did on the R27 as well. Add the helm door to the mix, and overall, the R31 is simply a big improvement in my experience. I can single-hand the R31 more easily and better than I could the R27.
Size/live-aboard possibilities: The R31 is significantly more livable for extended time periods. The walk-down-and-in master berth is worlds better than the step-down-and-crawl-in berth of the 27. Everything from storage space to elbow room is better, too, on the R31. If you are going to spend a lot of time on the boat, and especially if you are going to do it with one other person, the R31 is head's above the R27 in creature comfort.
Economy of operations: I now have 130 or so hours on the R31. My fuel economy is surprisingly close to what I got on the R27. I just finished 17 nights of Christmas Ships parading on the Columbia and Willamette Rivers. For the regular parade routes that we follow the first 15 nights, my fuel usage was basically the same as last year in the R27: 76.9 gallons and 58 engine hours this year; 77.5 gallons and 56 engine hours last year. (A lot of that is running at very low speeds, but there are some longer and higher speed runs too as we make day moves from one locale to another on the two rivers). The last two nights involve a long day run to Rainier, Oregon and Longview, Washington. We run at faster speeds, and this year I was going with other boats that ran at speeds that I would usually avoid (like 10 knots -- I do better at 12-14 or to drop down to slower speeds). So this year I burned an 29 gallons going to and from Longview (104 nautical miles) instead of the 19 gallons that I burned last year.
Maintenance: The first service on the D4-300 is at 200 hours, so I haven't gotten there yet. That compares to to the first service at 50 hrs on the R27 (which cost a small fortune at the local authorized service shop). So I'm way ahead so far. I did an oil analysis at 100 hours, which confirmed that I can go to 200 hours if I want to. I likely will change oil now that the Christmas parading is done, though, just because there are some standard break-in contaminants in the oil and I would prefer to change it sooner. All in all, everything on the R31 engine is much more accessible and seemingly much more rugged. The only repair I've had to do so far was to replace the stern thruster shear pin on one of our final parade days. I had some expert help in the form of some of my boating buddies I parade with, who collectively have amazing breadth and depth of boating and mechanical experience. But still, it was a relatively easy repair, and the access on the R31 was hugely better than it would have been on the R27. All in all, I expect to do more of the routine maintenance on the R31 myself because of the straightforward access it provides.
Hope that helps. If you have other questions, Bryan, either post them or PM me. I'll be glad to answer as best I can.
Gini
