Hi Kamel,
I also recently changed from Mashreq to HSBC.
Have just done my first big transfer to home country and am shocked to find it has cost me 1000 dirhams more than I expected. HSBC offer 1 free transfer home per month for EK crew and they can certainly afford to waive the 50 dirham charge when they charge such an exhorbitant rate. (Does appear to be around 4%)
Be careful to all the new guys joining. HSBC will come to your house to sign you up, but that is where the customer service ends and the rip-off begins.
Looks like I will have to go through the tortuous process off shutting HSBC accounts down and moving to Lloyds too!
For anyone who does elect to do that - step one is to get a clearance certificate from HSBC before then proceeding to HR Admin (visa services). (EK won`t pay your salary into any other bank until you have that clearance.)
Hope that saves you at least one wasted drive into town.