I have played just about every class on AO, with soldiers and fixers being my favorite. Soldiers do have alot going for them *cough* TMS *cough*, but for those not oriented for PvP, there are a few things lacking, that can be rather easily fixed.
what i noticed is that soldiers dont really have a buff that can help others greatly. TMS is self only, and by the time a soldier is able to cast his masteries, the other prof at his lvl have something better. Also, AC buffs are outclassed by MAs and engys, health buffs are blown out of the water by docs and enforcers, and shield buffs arent worth the IP and NCU investment (and even then, engys are better).
What soldiers need is something unique that is team-oriented, but useful for PvP... like a massive damage buff nano, or line of burst/fling nanos that can be cast by someone not at stratospheric levels... or more for the PvM crowd... a fear nano like what crats and MAs have. (heck, if i saw a soldier with a BFG and OP Elite on, I would run like a bat out of h***)
I have put my 117 soldier on sabbatical simply b/c its hard as heck for him to find a decent team, he cant PvP, and frankly BS missions get old when it takes 2 or 3 outings to level once, b/c of deaths (or stupid overpowered MAs). But, i will save myself the flames, and wont get on my "nerf MAs" rant.
Hopefully, someone at FC will take note of this... and everyone is welcome to post with their suggestions... and be sure to consider those who *dont* PvP, like me.