Agreed, 20' on a Hypnotist is crazy, in the wind it takes to get it in the air things will happen too fast. If you want to try something that short just for practicing ground recoveries, coin tosses etc. with then just go with some Polyester line, cut 50' off your SLK's reel, it won't miss it and you don't have to sleeve it either. Don't waste your money on Spectra because you won't fly
on 20's unless your doing indoor and you're not going to fly the Hypnotist indoors. I enjoy 50's when space requires short lines, I usually use 75'-85' and I feel disconnected on anything longer, that's me, as others have posted they enjoy 100+ foot, back in the '80's I thought kites had to have 150' lines. Preferences differ and often change over time.
If you can find somebody locally who carries bulk line and will make up linesets you could get a set of quality 125's at 90 lbs, you should notice a difference with a quality set of 90 lb lines verses the 150 lb supplied with the Hypnotist. If you find you don't like 120's then cut them into a set of 75's and a set of 50's. Alternately Steve here has the Prism Modulus lines in 90 lb @ 120'
, you can still get a set of 74's and 48's out of that if you don't like the 120's or Kent (Gamelord) at 'A Wind of Change', one of the forum sponsors linked on the right usually carries a selection of bulk line and will make you set of whatever you want.