I have been riding SS for a few years now mostly in the winter, its simple , reliable, looks better and allows you to get on with riding the bike not thinking about all those gears cables etc. Its easier for me though cos I live in Suffolk :).
Yesterday myself and a buddy went to the chilterns to try SSing a few hill, after much delberation I put three sprockets on the hub a 15, 17 and 19 with 32 on the front because it works with bash plate.
After starting on 17 and finding it hard going I swapped to 19 but found it little easier than 17 and lost out on momentum on the flats so went back to the 17. I normally have 32 15 in Suffolk and reckon that would still be ok. My mate rode 32 17 all day and only had to get of twice on bits that would probably had us off with a full set of gears.
We are both over 40 and Im certainly more into beer and pies than cycling so no whippet.
Conclusion is, we decided, singlespeed is fine in the hills and just ride what you brung.