I think playing at The Circle is the best option for all. Although Craven Park is a bit of fortress it has seen better days. I would think the opportunity for extra revenue and a full KC is too good to turn down.
Seems playing at MKM is purely down to crowd size and keeping it in 'Ull. Hull KR explain Hull FC venue swap for Brisbane World Club Challenge - BBC News
I must confess I have never been to Craven Park. Having said that I have seen numerous games on Sky and it is hardly a state of the art facility. Not a criticism but an observation.
I'm not a RL fan by any stretch of the imagination but even I know the new Board at Rovers have improved the ground massively. There is a new all seater stand at one end of the ground and an extra seating area/ stand was added to the East side of the ground only recently. I'd go as far as saying that more work and improvements have been made to Craven Park over recent years then we have seen at the MKM and there are plans in place for a whole lot more of improvements, especially behind the scenes facilities for the club and the community, adding value to the ground/club, plans I wish we had in place for 'our' ground. Plus the biggest factor, Rovers own their ground.
Rovers own their ground for now, it wouldn't be a first if the council/private sector had to buy it from them.