The Middleby 310 is the same as the 360, just has a narrower belt. We placed a few of them but in gas and they performed as good as the 360, just lower production.
I would pass on an electric oven and go with gas if you can. Gas cost less to operate and they perform better in my opinion.
The PS310’s are a 24" belt version of the PS360’s. The previous model was the JS/PS300’s which were of the same line as the JS/PS350’s.
I have found the electric Middleby Marshall ovens seem to cook the product drier since gas produces water vapor in the heating process.
To run these ovens are quite expensive normally unless your KW rates are low.
Middleby Marshall electric ovens are easy to convert to gas operation and reasonable. I would be curious if the blower motors are 3 PH. From the factory they come as 3 phase but if they have been replaced previously most service technicians will substitute them with the standard 208-240 Volt 1 PH 1/3 or 1/4 HP motor.
If you need more information on the conversion contact me for help.