I tried out my friend's Hardy Mach 1 line last year. Ever the cynic I
couldn't see before trying it what all the fuss was about & how the
line could make that much difference to the cast. The difference
between casting it & my line (standard Hardy double taper salmon
length) was incredible. Just to make sure it wasn't the paring with
his rod we swapped his line/reel to mine (Hardy 15'4" Elite) & it
worked just as well.

Needless to say I made a quick trip from the river bank to the tackle
shop (Mortimers in Grantown-on-Spey). Interestingly they reccomended
the regular length version of the line rather than the extra long one -
aparently it didn't handle as well.

If you are not in a rush to buy one a good place to do some testing is
the CLA game fair in July. All the major manufacturers are generally
there so you can try out different combinations of reels & lines. When
I was looking for a new rod a few years ago I turned up with my reel &
tried out most of the manufacturers offerings one after another. Was
very interesting to compare the different actions, although I did end
up going with the one I first though of.