I understand the point that tries to justify the change that's it's better for the economy or banks or whatever...
but actually this same point brings to my mind other very reasonable questions: (and I am asking these questions to the ones responsible for making that decision of changing the weekend):
1-How would overcome the problem of time difference, for example work starts here at 8:00 am , that would be 5:00 am GMT while in washington it would be 12 midnight!!!! So you are still losing common timing with many countries!!!!

2-What about losing trade with other arab countries??!!! I know it might not be that big trade as with Europe but you will difinitely lose a whole day of work with other arab countries.

Lastly I would just to add an advice to the leaders of this country,it's a Hadith (Saying) said by Prophet (spelling!!!!) Mohamed (Peace be upon him) and it could be translated as "This who initiates a good deed will benefit it's good return and will get the credit for the good returned to anyone who follows it, and this who initiates a bad deed will suffer the bad consequesnces of it and will be blamed for the consequesnces caused to anyone who follows it"