I think I will have to go with Neil on this one: buying a cheap front loader will come back to bite you in the kilowatts.
Elements in the door is critical:
because of the door design air is drawn through it when it gets to higher temps and static pressure builds: pushing it open ever so slightly.
3" insulation is also needed: even though you do not plan to fire over ^6. On larger models, extra power is required to heat, and thicker brick to hold it in. Front loaders are prone to hot and cold spots: added brick thickness, or added insulation helps to keep it even out. Smaller front loaders (6-8CF) are less fickle: the larger they get after this- the more heat zone problems there are.
An arched top does help: because heat in a front loader builds on the top. An arch top will keep excess heat above the top shelf, instead of building in it. A fan would not be a bad idea either: to keep the heat even towards the high end of the cycle; not to mention they take a while to cool.
For standard cone 6 firings they work fairly well: for technical glazes that require specific ramp cycles: not so much. However, doing a full cone pack in your first firing so you know where the hot and cold spots are is almost mandatory.
If you want to do large pieces: fire extra large bisque loads: nothing like them.