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Thanks very much for the information, I'll look into what will suit me best.
I'm currently just using my Gillott and only use 2-3 gears for most of the time and will check what these are as the AM could be good for me.
SideshowBob-
@SideshowBob I am on the same journey. I had come down tentatively on an FM as I wanted a low gear for the hills around me. @clubman good to read the alloy shells don't save much weight. I thought you'd said it was the weight from a lamp boss stopping you getting 59:59 for a 25, but reading back you blamed air turbulence :D
Edit: in case you haven't seen it, this is useful http://genetics.mgh.harvard.edu/hanczyc/pdfs/satriggersjuly06.pdf
veloham
My experience with Sturmey hubs is that they are generally reliable and almost impossible to wear out. That's not to say there are no problems.
Having only three (or even four) gears might seem a bit limiting, but it would be acceptable as long as they were the right three gears for your purpose. Unfortunately the AW ratios are not really suitable for anything. As you've probably read the differences are 25% reduction from direct drive and 33% increase: for example with 66" direct you get about 50" bottom and 88" top. Bottom is not as low as you want for the sort of machine the AW is intended for but top is too high to be much use except for conditions when you would probably choose to freewheel.
If only it was 25% up and 33% down!
Possibly Sturmey recognised this error when they came to the four speed FM and FW which both (confusingly) have a 33% reduction for bottom.
The AM is fine as long as you can cope without a low gear. It gives the equivalent of a 3 speed block with two tooth diferences (eg 14,16, 18). I have one of these built into a sprint rim which I found gave fairly good results (for me) in time trials. Being a three speed it's less prone to trouble than the four speeds, which can be a bit tricky to get into bottom gear.
You also need to consider availability of sprockets - there's no problem with the modern 3 spline type, although they don't wear very well. Other types may be difficult.
Finally, the shell - if you have adequate 40 hole rims - fine. All the FM and FW hubs I've seen have been 40's, and as we know this can cause problems. AW's can come in 40, 36 and 28 - it may be possible to change shells and internals, but don't know what is compatible. Don't imagine the Ali shells used on many AM and FM hubs save a worthwhile amount of weight - they are barely any lighter than the steel shells - the weight comes from the internals.
When I was young I thought these hubs were useless, now in old age I find I've grown into them - so well worth a try. Just don't attempt road races or chain gangs!