Hi Badboy
The project looks quite fine but I think you can arrange a bit the layout of the PCB. I do not know if space is very important or not but I think fitting the trafo on the main pcb near the switching transistors will be better and have shorter leads. I think you can make the control circuit on a separate board and fitted with a pin header. You can also make more than one pin header. This will save you space and get also low profile.
I am glad you found the problem, 50 degrees is very normal operating temperature.
Regarding gate resistors I think using a separate resistor for each fet will be a better choice thus the gate charge will be more equal to each fet. Doing it this way you will need to use a 6 ohm resistor with each fet thus having them in parallel will bring the total resistance of 3 ohms which is seen by the IR2110
Some considerations for gate resistor and snubbers. I have a blog post here and shows step by step how to work out the gate resistor value according to the fets used and current handling of the fet driver (IR2110 in your case) This chip can deliver a maximum of 2amps of drive current so this must not be exceeded. Do not forget to double your values as now you have 2 parallel fets . You will also find how to calculate and adopt a simple resistive and capacitive snubber for the smps in the same blog post. Download the pdf in the post its all explained there.
Link http://www.diysmps.com/forums/entry....gate-resistors
regards Silvio