gearupflapsupshutup,
The extra maids room can be used as a bedroom, certainly in Arabian Ranches Al Reem (the 'cheap' houses), the maids room is about the same size as either of the kids rooms upstairs. I would at least take a look at the less fashionable areas like Mirdiff, Jumeirah Village Triangle, etc for cheaper options too. The agencies are now putting up properties here for 170,000/yr when previously they were around 140,000/yr. A 30,000/yr increase. That is a big whack, plus the 5% agent fee plus the 5% deposit.
If any of your kids are in secondary school, the education allowance does not cover the cost of schooling here. You'll be looking at around 5000 AED+ per year/per secondary school kid increasing with age. That is for a very good and long standing not for profit school, I'd guess GEMs et al are going to be more. School fees going up 5-10% too.
Long and short. Moving and living in Dubai is expensive. You earn more than you would in the UK (or wherever), but it just plain costs more too. From the expected cars, furniture, rent to the unexpected cost of some basic items, fees, tolls, fines and moving expenses due landlord issues...it just plain costs. Don't expect to save much in the first couple of years.
The company has said they are looking into rent and school fee increases, hopefully there will be some good news on that soon.