I went ahead and ordered the combo ticket, couldnt justify an extra £60 "just to be on the safe side". Anyway they came today, there are 2 tickets instead of one and thats it. One ticket is the Anhauscer (sp!) Busch side and the other is Universal/IOA/WnW etc - just for the sake of 1 less ticket they charge so much more!
And, in the letter i got with the tickets it said that Complete Orlando was its sister company! And on the back of the letter it had the address which started ATD something-or-other which is Attraction Tickets Direct - so it seems like they are all connected anyway!