I think you should stick with your min/max instincts and stick with your Traps/Son Defender. You are able to pick up the goodies out of Traps a lot sooner compared to Corruptors. Traps is good for corruptors, but at lot of the important tools you need for the set to work come a bit later which may hinder your desire to level the character/avatar you have.
For example, by level 26 you will have access to Trip Mine, Seeker drones, Poison Trap, Acid Mortar, and Force Field Generator as a defender which improves your ability to solo dramatically, but also your contribution to your team. The Corruptor side you have to wait a bit longer to obtain Poison Trap (20), Seeker Drones (28), and Trip Mine (35).
Naturally Corruptors obtain their blasts sooner than Defenders, but Seeker Drones, and Trip Mine really changes how a Traps Defender/Corruptor plays dramatically, so you probably would be more inclined to stick with a Defender seeing you obtain the goodies sooner. Sonic functions rather well with the lower level blasts anyways, so I think you are on the right track. 
I'd go Fire/Traps corr or Traps/Sonic, Ice blast just isnt super awesome like fire and sonic are.
Corr traps vs Def Traps
Webnades, Caltrops, Triage(technically slightly better cause corrs have higher base hp), and Poison Trap are all the same between Corrs and Defenders, ie the defenders don't get a bonus for it being their primary.
Acid Mortar, FFG, and Seekers are better for defenders, and the difference is significant.
Trip Mine and lolTime Bomb are better for Corrs.
It's harder to soft cap a Corr because of the lower numbers on FFG, CJ, Maneuvers, and Weave. Corrs can get to ~34% defense using the above powers and steadfast/glad armor uniques. Defenders can hit 43-44% to EVERYTHING with the same powers and IOs.
A Fire/ Corr will do very nice damage though, way more than the defender, although you have to factor in the extra 6% resistance debuff from Acid Mortar and the -res from sonic.
Just food for thought.
I'd go with Fire/Traps. Bit more versatile I think. Especially if youre a min/maxer and are willing to put in more money.
I am looking at 3 and Just cant decide.
Min/Max is my major problem.
I would like one AT that I can build to 50 and keep.
Traps/Sonic Defender
Fire/traps Corruptor
Ice/traps Corruptor
I want to solo
I want to group
I want to be able to take down the tough mobs later
I have tried everything in the game
Tanks
Scrapers
trollers
Doms
etc. etc.
but I keep getting pulled back to this corruptor/defender role.
now I am so torn between those 3.
I have been playing this game off and on since release and still dont have a level 50. (so sad I know) I just cant seem to stick with a character.
I am back with GR and still cant get someone to 50.
I am working on a traps/sonic right now but I am just not sure if I should be doing this or a corruptor.
I am a min/max player and just end up going back and forth.
anyhow thank you very much.