What's stopping you from taking it? A 40% increase in pay and an additional 10 days annual leave makes me wonder what there is to consider.
Would you lose flexi-time? Presumably.
Did you apply for HEO recently or AP in the Civil Service, if not, why not, if yes how did you get on? How long have you been an EO?
With many more open competitions in the Civil Service moving out to the Public Service won't impact on your ability to apply for those jobs as would have been the case in previous years, so that's a plus. However, depending on the age profile of your potential new bosses you could have a wait for your next promotion internally.
There is the possibility that you could be "stuck" in that (presumably) small enough work area, does your work commute change for the worse?
No-one who doesn't work in the unit currently can really give you advice as to what it's like to work there.