T2 is an excellent supplement.
I don't think it was actually pulled off the market and made illegal or anything. The FDA was just having trouble with Thyroid products (perscription and supplement) and so just put pressure on those making T2 to quit.
It is definetely stackable with ephedrine and the current replacement. The ephedrine types work through different pathways than T2. However, it's not recommended to be used with HOT-ROX as HOT-ROX has a thryoid boosting effect and they may interfere. It's recommended that HOT-ROX be used post-cycle to help prevent thryoid suppression. Since you need 4-8 weeks off from T2 anyway, this makes sense. T2 isn't that suppressive, but if you take too much or for too long it is. Best to be safe.
The max dosage on T2 is 150 mcg, however 300 mcg is still pretty safe, and T2 has probably degraded to about 90% effectiveness now, so it may need a bit more to be effective. However, start at 50mcg and work your way up every 3-7 days adding 50mcg and seeing how you feel. I probably wouldn't go beyond 350mcg. 200-250 is pretty effective for me.
Also, it says to discontinue after 4 weeks, however it's probably okay to go as many as 6 before stopping, depending on the dosage. I'd be careful though. Probably be best to do a 4 week cycle of 200-250 mcg and assess effectiveness, and then for the next cycle experimenting a bit.
Depending on the condition of your thyroid and how your thyroid runs things, you'll get different results. The thyroid effects a lot of different parts of the body so there are a lot of things that can happen. It can increase metabolism, lipolysis, protein turnover, etc. Some people lose fat really fast, others it helps add muscle.
Hope that helps.