Your description of Bailey is so familiar that it is scary. I applaud you in consulting with the most experienced / effective people that you can, whether formally or informally, to come up with a plan that is appropriate for your situation and for Bailey's temperament.
I finally spoke with my vet this summer about reactivity and medication, then followed up w three trainers locally that know Snap from the various classes that we have done / do.
My vet is reluctant to prescribe any medication, believing that it is to be used a last resort. Among other things, he suggested that as positive as I am, I may have actually confused my dog regarding the "corrections" that I do. While I didn't want to hear this, the conversation and subsequent discussions did prompt me to do a lot of soul searching and to rethink training methods, reinforcement rates, techniques for dealing with leash reactivity, impulse control, what I want from my dog, and what is good for my dog. **
I thought that the answer might lie with consultation with a vet behaviorist, but I frankly was dissuaded by one of the trainers in going this route. *She accompanied a client to see one at a vet school a few years ago and frankly found the advice to be very expensive and not worth the cost.
For now, I am revisiting some of my favorite booklets (Suzanne Clothier) and DVDs *(Patricia McConnell's "Treating Dog-Dog Reactivity" *and Grisha Stewart's "Organic Socialization) and working on making tiny improvements in management / retraining behaviors - habits. *Incidentally, I also have the Manners Minder and have successfully used mine at the office to reverse reactive behavior (when the front door opens, Snap now runs for his bed where the Manners Minder is, instead of barking at the intruder).
In lackadaisical hands, Snap might have ended up in rescue. *In my relatively inexperienced hands, this smart, "overdrive" dog (at age 3 1/2) is still a work in progress. *And by the way, I would not give up on Therapy Dog work. *Snap is a therapy dog with a large repertoire of tricks and the drive to do them. I have no doubt that Bailey could do the same.
I'm so sorry that you don't live closer... I'd recruit you to join my Sunday morning breakfast dog-folks group. *It's our own form of therapy.