yes, it would be easier potentially. but it all depends on what fits on the car (HOnda CRV). a TWE is the likely candidate for the middle seat, but we will see if it fits given where dh/I have the front seat position (if needs be, dh can be relegated to just driving his car at weekends - no problem with space there, as huge people carrier type, with individual seats and isofix on all of them)
dd1 needs an extra harness to keep her safe, as she wriggles out form under seatbelts, so that is another consideration.
currently dd1 and dd2 are both in isofix seats, but that will have to change in all likelhood due to space.
one concern I have for 2 rf seats - how does the child get into the middle rf seat without climbing over another seat (with muddy/wet shoes for a good part of the year!) I can see poor dd1 ending up with a soaking wet seat whie dd2 clambers all over it having splashed through several puddles etc. 
I have an appt with the lovely ladies in Milton Keynes on friday, and hopefully they will come up with a solution. I am keen to keep dd2 rf, as she only weighs about 15.5kg, so I would rahter keep her in the lowest rated seat for that, ie where she is!