Planning to get a coffee grinder costing about 2k from a distributor directly but downside is they do not accept credit cards at all. Came across maybank latest ezycash promotion with 3.88% cash advance fee.

I do have the cash to get it one shot but was planning to pay it with a credit card & BT to another bank with 0% fee and pay it using installment. Would this ezycash be a better option since cash advance fee would be around RM77.60

Yep, the amount u charged to your amex will appear in your statement. In fact not only amex, petrol stations hold a certain amount for other credit card as well.