OP, here's a suggestion: Don't go up to 2.5mg. In fact, I wouldn't go higher than 1.0mg if I were to ever run letro again. It's some powerful stuff, and the sides just s-u-c-k. I know all about the cycle posted on various forums that lays it out that way, but trust me, if you take it up to 2.5mg, you can say goodbye to your sex drive for a while and you will just feel like total sh#t. Letro eliminates around 98% of estrogen in the body, so you won't need to dose high. If you're inclined, you will have the luxury of staying at 1.0mg longer without noticing sides, which will allow for a greater chance of permanent success.
Whatever dosage you decide on, your joints will get pretty dry, so make sure you up the fish/flax/olive/etc. oils. Also, make sure to taper down very gradually with the letro to avoid rebound and then go to a SERM, which you should also taper down as well.
I am a letro success story, by the way. I experienced estrogen-rebound during PCT on an Epistane cycle. My lumps reduced at the 1.0mg dosage, but I continued to follow the suggested protocol. However, the sides kicked my as# for the rest of the cycle and I felt absolutely miserable.
Good luck.
P.S. I hope when you say gyno, you mean painful, sensitive lumps... and not just puffy nips.