"They're much like normal biles otherwise and I presume exactly as comfortable."
Comfort comes almost entirely from the tire size and pressure relative to rider weight and road conditions. The frame is largely irrelevant, at least for anything made in the last few decades by any half-competent company.
"Getting the bearings and power transmission were apparently the harddest bits."
Getting alignment on these items is the hardest bit. Bicycles require an incredible degree of proper alignment of a couple of key components in order for things to work right, mostly shifting, but also handling-wise.