Consider also that there is a difference between riding fixed and riding SS - the addition of a freewheel changes things and it's not just in the ability to coast.
You do have a lot more control over your speed on a fixed bike and you do exercise it a lot more. The question is, is this just a source of satisfaction or is it a serious advantage? I'm never likely to ride in snow or ice (we don't get it here, a very cold day is 10C where I live) so can't answer that question.
The other thing to note is that, for reasons I've never been able to understand, the power delivery on a fixed bike is different to something with a freewheel with the result that, up to a point, you don't 'need' the extra gears - I ride rolling routes on my fixed gear bike without thinking about it or feeling the need for extra gears yet that same route has me using everything except my granny on my geared bikes. However, you will eventually come to a hill where you do NEED to go down a gear and if you have one or two of them on your commute, fixed or SS isn't the way to go.
I personally think that if SS will work, fixed will work better, but I don't mind spinning down hills and don't miss the opportunity to coast.
Maintenance? I think that depends on how fussy you are. Me? I'm slack and any bike is filthy by the time I get around to doing something. Yes, fixed or SS is a lot easier to clean but considering that I hate doing either, it's probably not much of an issue. I feel your concern about the drs though.
How's this for a suggestion. Convert your bike to fixed or SS either by buying a rear wheel or just going for a suicide hub (safe enough if you use your brakes to stop) and just run off one your existing chainrings (don't remove the other). Fitting gears is an afternoon's task if you decide you want them. Even if you're forced to redish the rear wheel, that's not a problem. The initial conversion of my Europa was reversable simply by bolting the bits back on - she only become more specialised after I realised I liked this fixed game. One thing's for sure, you won't know until you try.
Richard