I agree with what onetime said...maybe not 5lbs for every 1lb that test gives you, but still better results mg for mg. But it's also more expensive, mg for mg. So there's that to weigh in too.
But since it's a 19-nor derivative, it's not very estrogenic in and of itself (the 19-nor derivatives don't aromatize easily, though they can, if you crank doses high enough...you ram enough of anything at an enzyme and you're bound to get something done, but that's off-the-charts tren use we're talking about). More likely, the other drugs you take with it will find the aromatase enzyme and be converted to estrogen derivatives. Tren is a hog at binding androgen receptors, and the other shit you take with it will either get cleared from the body, aromatize, reduce to a DHT derivative, or just stay bound to the globulins in the blood. The body doesn't work in absolutes, of course, but that's a likely outcome.
The 19-nor derivatives are also weakened when they come into contact with the reductase enzyme in sex specific tissues (i.e. scalp, prostate, skin, etc...). So, androgenic sides are weaker too. Again, not to say it isn't possible, but it's less than what you get from testosterone, mg for mg. When 19-nor derivatives like tren hook up with the reductase enzyme, they get converted to weaker androgens that don't have much binding affinity for the receptors in sex tissues. That's good...they can't bind as easily, so signals aren't transmitted as easily. It can still happen, mind you, just not as efficiently as when test reduces to DHT.
So, tren is a pretty safe drug (I know it has street cred for being harsh, but I always wonder about that). I have used tren, got great results, no discernible sides, and felt great on it. It's a bit pricier where I come from, and not always easy to get, which is why I wind up sticking to good old test.
Given my druthers, I like stacking tren as my 19-nor derivative, Masteron as my DHT-derivative, and methandrostenolone or oxymetholone as my 17-beta (read: test) derivative. When I can't find 17-beta derivatives, it's plain old test.
If you can't grow to 200lbs at less than 10% bodyfat at 5'10" or less on 150 mg week of tren, 100mg a week of masteron and 250mg a week of test, you should try golf or billiards.