I actually feel very well just on the T3 and have a friend that's on only T3 and she feels even better (because she's lucky enough to have had it help her lose 60 pounds).

A year ago I was non-functional in the afternoons, up all night and even more tired by morning. Since being on the T3 only, I no longer have the afternoon drag, and I sleep like a baby at night. In fact I now look forward to going to bed like a normal person instead of dreading it like I used to.

I am only starting the Armour just to see if that's what I need to lose some weight. As of 2 weeks on it, I feel nothing from it--either good or bad.
Only time will tell I guess, but I definitely am better than I used to be just on the T3. It has suppressed the TSH, lowered the FT4 and increased the T3 (which is the fuel your body needs). T4 gets converted into T3, so yes it's important, but it ends up being T3 anyway. That's why my Dr. originally skipped the T4, he said your body is gonna make it T3 anyway, so he supplements with Cytomel. It was at my request he add the Armour--just so that I can see for myself what happens with it.