I rode the new Spa Steel Audax today for the first time. The weather wasn't great, but the bike revealed itself to be a beauty. The frame is comfortable, compliant and fast; the carbon forks do a good job of soaking up some of the road noise. It handles nicely, and does feel quite similar to the Thorn Audax Mk3 in terms of general ride, although the latter's steel forks are more my style. I may well invest in a pair of steel forks in the near future. The thing that particularly impressed me was the lightness and climbing ability of the bike; it dealt superbly with the pedalling effort when I was climbing gradients and feels significantly lighter than the Thorn, though that may well depend on the build specified on either bike.
Mine has Deda finishing kit, 105 triple chainset, levers and rear gearing, tektro brakes, rigida Chrina handbuilt wheels and a pair of Schwalbe Lugano tyres - all translating into a very well specced bike for just short of £1300.
All in all, my feelings are that if you're open minded about which steel framed bike to go for, then consider the Spa as well as the Thorn, it's terrific value.