You could get a bike that offers both, Vision offers there bikes as both USS and ASS. The R-40 can also be switched from LWB to SWB. Some of the Burley bikes can switch from LWB to SWB as well
I dont find any of my recumbents twitchy (Vision R-40 SWB/USS, Longbikes Slipstream LWB/USSorASS, Bike-E, RANS Sceamer, Hypercycle SWB/USS, Homebuilts LWB,SWB,CLWB) Only the Hypercycle takes any real skill to ride, due mostly to the fact it was just a really bad recumbent.
I find I do like the USS more then ASS, in fact I'm thinking of building a USS set up for the Screamer. For speed ASS is more aero then USS.
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." - Arthur Conan Doyle