Well since we're onto the pros and con and whys... and all this comes from a southerner - the Chilterns aren't the most fearsome hills.
SS does take some getting used to but it's probably not as hard as some might think. Mainly since (most) SSers don't ride the steep, technical climbs that geared riders think of as the hardest climbs. If I ride my SS on group rides there's usually the odd walk up a steeper hill but there's usually another rider going at that sort of pace anyway, it's fine.
You'll gear it for the hills you have locally and spend a lot more time spinning an easy gear so it's more a case of saving your energy for a few harder efforts in the ride. I've tracked my average heart rate on a longer 'for fun' SS ride and it can be a level lower than a similar attitude geared MTB or road ride. It will spike fairly high but the general level is lower. There's a limit to how low a cadence you can climb at before you stall, or (locally for me at least) there's a limit to the number of hills that are just right to keep you at threshold and make it a really hard effort. They're often optional on a solo ride anyway. All in all I'd say it just redistributes your effort, rather than it being harder overall.
My favourite bike is my rigid 29er SS. It's been my main MTB for almost 10 years and has only had a the usual chains/rings/BBs, brake pads and rotors and tyres in that time so it's worked out very good value.
I love the simplicity of it. I can ride it a lot in winter w/o wrecking it. It's quiet. It's always in the right gear for getting out of a corner fast. Riding becomes about momentum and carrying speed more than what gear or pedalling so it's made me a smoother rider. I know it'll sound stupid but rides on my rigid SS have more of a flow to them, it's more engaging even if it's slower in many places. I couldn't say "less is more" and keep a straight face but there's something in it.
Single-speed is never having the right gear... I really don't understand the attraction for anything other than a city bike.
SS on road is a bit rubbish tbh, unless it's a regular commute or around town use as you say. I thought the speed range was too high on road for one gear to work well. For some reason the idea of SS road touring has always appealed to me though. In reality, it wouldn't : )