I have five lateral mosfet ampliiers that I use for PA. So when they are used they are used hard!
The biggest has 8 pairs of Hitachi 2sk135 / 2sj50 per side. C-audio SR707
This amp did fail but was seriously over voltage, and had been used as a 4 ohm bridge producing 2.4kW.
http://www.diyaudio.com/forums/solid-state/150675-maximum-voltage-mosfet-output-stage.html
The next biggest has 4 pairs of 2sk1058/ 2sj162 per side. Rauch DVT 250s. 550W /4ohm per channel.
None of my amps have source resistors, and they are (now) reliable!
All of them are based on the hitachi app note circuit, but have an added driver stage for the fets.
Lateral mosfet amps are not prone to thermal runaway, and the mosfets are quite robust.
I know from experience that when the cooling fan has failed during a gig, and the amp has completely overheated, that there is no thermal runaway. The amplifier limits itself and sounds fuzzy but it does not die!

The logic is quite simple - The device that is drawing the most current heats up, and turns itself down balancing the load. I would recommend matching your output devices to minimise this. Usually if I am rebuilding (recapping & tweeks mostly) I measure all the fets and group them to minimise the imbalance.

I cant see you will have any problems with 2 pairs per side.