Did the mechanic plug it into the Suzuki Diagnostic System? What was the fuel pressure and volume? Extremely unlikely that the ECU is at fault. There are many things they should be looking at first.
No he didn't - so I'm going to a Suzuki dealer to see if they can do better.
Camel or others would know better but I know the manual hasn't changed since 08
My guess would be they are the same and a swap is doable.
You cant do a straight swap as the Key is registered to the ECU through the imobilizer so you will need to get one of the guys to flash the Ecu so the imobilizer want block it from working
Camel can confirm this