Loft conversion - one big bedroom or two small bedrooms?

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We are in midst of dormer loft conversion.

Need to decide: one big room with separate bathroom or split (non-loadbearing wall) big room into two for kids?

Facts:

• currently living in 3 bed Edwardian mid-terrace
• 3 kids (10,8,4) who may want their own bedroom one day
• 3 bedrooms on 1st floor - one reasonable master, one slightly less and one small third bedroom (not large gap between single bed and chest of drawers opposite)
• nice area in SE London
• no plan to move unless absolutely necessary

My husband insists it split into 2 beds. So each kid gets their own bedroom equally (to an extent) without one hogging largest bedroom.

I may inclined towards 2 bed split, although I'm a style over substance person and would abhor scramming too many rooms into ordinary 3 bed house)

Any cons to consider?

How do you families with 3+ kids in their tweens/teens live in terraced houses with lofts?

Thanks so much in advance for any ideas!

Not to mention flushing a loo!

Have any of your neighbours done a conversion?
I found that planning ours was made hugely easier by being able to have a nose around a couple of similar conversions down the road.

We did 2 rooms- still have a very impressive master (super king bed and loads of space around it) as a Lshape- with a row of fitted wardrobes in the narrow bit/velux at end and a tiny little 2nd room as a guest room that nestles into the sqaue space created by the L shape. And a very generous bathroom up there. So so glad we did it. So much more practical/felxible than just 1 huge master IMO.
Have been able to have so many more fiends stay over and like now with DH with chest infection coughing all night, he sleeps in guest room. So ours went from 3 bed to 5 bed.
With the right styling/planning/decor you can still make the larger room feel like a grand master suite and turn a tiny room into a cosy stylish guest room too.

I would want the master in the loft and leave the kids to it on the middle floor. With a planned rotation of rooms over the years if needed to be fair.

Our neighbours put two rooms in the loft, one was ultimately too small to be useable and the next people just changed it to one.

We need to know the sizes of the rooms.

Electric shower means less stress on your boiler and also a hot water source if the heating fails!