Bigger is better. Both are fine boats, but when we had to make the same choice back in the day, we liked the layout of the H34 more. As I recall, the aft berth area didn't really close off from the salon. The H34 has a bifold door. For us its not so much a privacy issue as much as I don't have to look at all the stuff we have crammed back there. The head area is larger, which is nice. I think the H31 has the holding tank under the v-berth. That never sounded optimal to me...maybe the H31 owners didn't have an issue with it. We changed our holding tank to an ElectroScan anyway and couldn't be happier. The H34 has a nice double sink in the galley. I don't know the comparison with the iceboxes, just that we can get 60 lbs of block ice, 5 lbs of dry ice and 5-6 bags of cubes in ours plus a week of food and it still has ice left at the end. Also, more opening hatches on deck makes it cooler in the summer. The hatch over the head area is good...the solar shower hangs right over it, so its just like using the regular shower. We keep that hatch cracked open all year round and it keeps the inside of the boat well ventilated. If it rains, it just goes into the shower pan...easy to deal with, and no damage. The H34 anchor locker is molded inside to hold both a Danforth anchor and a Bruce plus the line and chain for each. Kind of nice. I don't know if the 31 was set up for two anchors. The 3 cylinder Yanmar is smoother running than the 2 cylinder version. I think the later versions (towards the end of the run) had 30 horsepower engines versus the 22 horsepower that my '85 has. Tankages are correspondingly bigger which is convienient.
Allan