I wouldn't anticipate any problems for BMI Baby making a success of a two-aircraft operation out of MAN; the no-frills market there is far from saturated. MAN-FAO is actually served daily by Monarch Crown Service [3x weekly rising to daily in Spring]; this is a "with frills" operation but competitive on price, reports of the service are positive. It is interesting that Baby have chosen to go head-to-head with Monarch on the three other Crown routes though [ALC, AGP, PMI]; I'm sure there will be plenty of business for both but I would have liked to see some new destinations on offer.
Best of luck to both Baby and Monarch on their new programmes ex-MAN.