I have a T-962 and although the "community" firmware is an excellent upgrade, the oven is still uneven and is likely to overheat areas of your PCBs. You can see this as white silk will turn a colour that varies from cream to light toast!
By the time you have added extra insulation, removed the masking tape and applied kaptan tape, checked earth bonding, wired a ds18b20 for cold junction compensation and finally flashed the great new firmware; you might have invested the time & money in a better solution.
Added to the above comments, the T-962 has bad insulation on the door which can't be replaced easily, if at all, so the handle gets too hot. The bottom has no insulation either so looses heat and the tray on which you place the PCB is not flat as the result of the bending process during manufacture.
I made a convection oven and the results were amazing when compared to the T-962 which has the heaters too close to the board.
A 20L (220mm x 320mm x 210mm internal dims ) oven with 1300W IR with 4 tubes 2 top 2 bottom. From my experience 1300W is a minimum, I need to run the oven once to warm everything up or a RoSH no lead profile isn't quite met, but when it's warm PCBs are perfect every time.
I used a controller from reflowcontroller.com, however I can't recommend it. The board is basically OK, but the all important software is another story. I plan to do a review of it in future, but don't hold your breath.
Like many, once you buy and use a controller you will probably decide to build your own as they are never exactly what you need.