You might be better off with 25m if that "feels" better.
But give the 20m ones a try for a longer period, to get used to, as others say
You dont write if you are on a bridled kite or not as there can sometimes be 2-3m difference in total length, so important
I dont think pinching or similar means anything at all, with these lengths we are discussing here - and kite R&D is not just high tech rocket science.
Personally I dont like lines shorter than 20m, as it gives such an uncomfortable feel with on/off and no smoothing of the power at all
So you dont get the fluid motion like used to with a bit longer lines
Others love this power dump feature
And reverse, longer lines than 19-22m (+ bridles) and the kite becomes a slow hot air balloon instead of a precise tool for waveriding
Give it a try Tony, use the short ones a little longer !
(unless you are on a non-bridled kite, where 20m is more like 18m which can be really difficult sometimes)
I dont know - but assume you are not waveriding unhooked...
The kite and the riding style is also important though:
If you ride with kites that has a lot of grunt or C kites, you can not powerdump much with the bar, and you might like shorter lines instead and have to live with the disadvantages - but you can dump the power faster now.
If you dont "use" the kite, but would rather surf without it - you might also prefer really short powerdumping lines.
If you use the kite as a tool for "everything" out there, in conjunction with your ride, you will often like slightly longer lines.
Actually, I might go against the current regarding the "big kites longer lines" that some advocate, and prefer almost the opposite
As when the small kites are out (4-5-6-7m2), it is typically really gusty and you like a kite combo that can mellow this out instead of a raging on/off turbulent ride.
You also need/want a bit of powerstroke if huge lulls.
Whereas the big kites from 9m2, can be speeded up in reaction and feel with shorter lines, so I dont ever extend my lines with kites from 9m2 and up (only in super light wind but that is another issue)
But give it a try a bit more and see what you'll find Tony !
Dont think you are wrong in ending up liking 25m lines the most, as there are many ups and downs for both lengths when waveriding.
Just give the 20m a serious try first, as the feel and difference takes time to adapt to