Am using a 2GB that i found down the back of the sofa when i moved into my house (i dont believe in buying memory when most cloud services give up to 15GB for free).
No overheating problems apart from when i powered on for the first time (was a hot day).
I choose sd cards over cloud any day, in fact I have never used any could services.
I will always buy a phone with sd card over a phone without it.
The truth is they are going to stop making phones with sd card access.
They want all your information on the phone and unable to remove it by using an sd card.
This in combination with a non removable battery will secure their chance in getting all your information.
I will never buy a phone that can't have the battery removed.