1)How much better stopping power are they than full sized V's if at all?
About the same as a very well adjusted set of Vs - but less finger pressure for the same stopping power - dead easy to adjust on the road without tools so generally much better than a worn set of Vs2)Is the modulation better than V's?
Miles better3)Is there any chance of fluid boil on long descents?
has never happened - as far as i know - includes long descents off some big alps4)Are they easily repaired/maintained at the roadside and at home by the owner?
Don't know - the only maintenance I have ever done is to twiddle the adjustment screw occasionally and change the pads 5)are they better in the wet than V's -
From my experience yes - very positive but well modulated in the wet - on long descents a quick dab normally clears the rim of water I started off on cantilevers which on new pads and superbly adjusted were OKish but rubbish as soon as there was any wear or in the wet - went over to Vs when they first came out - a definite improvement - but ditto when they start to wear they become less efficient unless you are constantly adjusting them - plus in the wet I tended to use a lot of pads (the black Maguras I use go on for thousands of Km)
My hands have never been very good - even with Vs on long descents and a lot of hairpins my hands and forearms became very tired - changing to the Maguras solved that - going into hairpins I can scrub the speed off without much effort - plus I like that they are very positive - takes some of the effort out of handling a heavy bike in heavy town traffic - Im a fan unless you missed that part
that anyone would go on a multiday tour outside of the area that they are familiar with and not take a map