I would like to know if the 24mm and 28mm lenses gives good results on it (if I'm not wrong I remember they are optimized for the 37x49mm sensors, isn'it?).
Yes. All lenses with a name starting with HCD
are optimized for these smaller sensors. Lenses covering the full 645 frame are called HC.
If someone had a chance to use them with a HTS it would be great to know how they behave with it and how good is Capture One to deal with it.
No idea how they behave with capture one, but I should point out that the lenses will cover a bigger frame when mounted on the HTS (or you would not be able to shift), but they obviously vignette when fully shifted. Phocus will correct that automatically using the tilt and shift values stored in the exifs (and will also correct distortion, etc...). I don't think that these values would be stored when used the H4x, however.