Here is my two cents on Fire and Elec.. One of the reasons I believe people find Fire and Elec harder is because they do not have any defense based powers built into their sets. They are pretty much all resistance.. This makes it more challenge to add defense into their builds especially since many people try to get defense to as many positions or damage types as possible.
Fire's best defense is a good offense... a Fire/SS should be Foot Stomping and Burn Patching as many people as possible... take them down quick..
The trick I learned with Elec was not to build in more defense.. but to build in more recharge and get Energize as close to perma as possible.. my build was off by about 2 seconds.. He has plenty of resistance and could spam a heal if need be.. this make him tough to kill..