I also ordered the re-issue of The Dark Third and listened to it for the first time yesterday. I love that it is essentially one long piece of music since every song flows into the next. Sometimes you don't even realise it's a new song.
After one and a half listens, it's impossible to say if I like it better than Eupnea. I love the vocal arrangements and I think they're actually even more imaginative and complex than the ones on Eupnea. This band is about melody and not about technical wankery but still all the arrangements and instrumentations are very tasty and performed well.
Side 4 of the vinyl re-issue also contains the original EP featured with the first InsideOut release from 2007 (except for one song). Once again, InsideOut doesn't disappoint with the vinyl issue. Sound is broad, transparent and there's no surface noise. Very happy with this purchase.