After you account for the offset from that flat antenna, you should definitely have much, much higher SNR. The antenna gain of the MK1 is about 12 dBi, whereas the flat antenna is 26 dBi (if I remember correctly). The thing to remember, though, is that the higher the gain, the smaller the beam width, which makes pointing more difficult.
When you are talking about 1m reflector, the aperture of the antenna is the dish itself–the LNB (MK1) is largely irrelevant. That 1m aperture yields plenty of gain (~36dBi?), but also a really tiny beam width (~2 degrees).
My guess is that the flat antenna will work, it will just take a bit of trial and error.