Honestly I don't have the time to read the whole thread right now, but I read the original post, and thought I'd chime in quick, so I apologize if anything (or everything) I say has been mentioned.
First of all, if you are injecting suboxne you should get a micron filter, you'll be doing your veins a big favor this way, and I can't condone you continuing to inject suboxone without one in the spirit of harm reduction.
Now, if you do have micron filters, I would continue to taper IV for a while, because in all honesty, it is the easiest way to accurately measure your dosages and know how much you are getting as the BA is pretty much 100%. The current dose you are on now is very high-to put it in perspective, sublingual absorption is only 30% of IV (which is full absorption). So 2mg IV is equal to roughly 6mg of suboxone sublingual. You mentioned injecting about four mg a day, so that would be similar to quitting a 12mg sublingual habit, the only difference is you will feel the withdrawals a bit sooner.
When I first started to IV suboxone, I was easilly able to jump from about 16mg sublingual, to 4mg IV, and then to taper down to 1mg IV/day. What I would do is to start making your shots smaller. If your doing 1mg shots, try out .8mg shots. I almost GAURANTEE that you will not be able to feel any difference, you could probably even drop down to .5mg per shot without much discomfort, the key is to keep yourself busy.
Once you get to the point where your .5 mg shots are feeling good and keeping you stable, try to subtract a shot from the day. If you were doing four shots, lower it to three. This will seem hard at first as we tend to condition ourselves to "needing" a dose at a certain time, but if you keep yourself occupied, it will not be too rough. After all, bupe has a long half life, and the ammount that you'd be taking per day at this point (1.5 mg) is still a relatively high dosage.
Once you get down to three shots a day, I would once again try to lower the dosage of each of your shots. You can probably drop by 100 micrograms every four days or so with little discomfort. If you find yourself feeling a bit uncomfortable at a dose, bump it back up 50 micrograms, and taper a little slower. I would not think about switching to tramadol until each dosage was around 70 micrograms. Tramadol is a very weak mu opioid agonist, and it also can cause seizures in high dosages, so you don't want to be popping tons of these things to feel normal. When your total buprenorphine intake is about 200 micrograms per day, I would test out a few tramadol (make sure you look up the safe range for dosing, I don't know it off hand). If the tram's seem to be effective, you can switch over, but I would try to use them sparingly, and rely more heavily on the soma and the clonadine. Even though tramadol is weak, it's been known to have some of the worst withdrawal symptoms, as it also has serotonergic properties-you don't want to just switch addictions. Anyway, I hope this is helpful. The key to success when tapering is to be patient and forgiving. There will be bumps in the way, you just got to pick yourself up and keep on truckin'.
Also, if you want to switch your ROA, make sure to look up the BA for each one. Sublingual is 30%, rectal and nasal are both around 50%, and sublingual with alchohol is 50-70%. I prefer to take my suboxone sublingually now, as I only dose 2 times a day and it lasts longer, but the downside is that it takes me longer to adjust to a dose, either way, your going to want to stick to primarily one way of taking the buprenorphine.