Tren E is softer in terms of it being a long acting ester. The problem is that you may not feel much from Tren E at first, then when it kicks in 3, 4, or 5 weeks later if it doesn't agree with you in some way then your stuck with those feelings for 1, 2 or even up to 3 weeks until the ester clears your body. Whereas Tren A sides may only last a few days to 1 week max upon cessation generally speaking.
Tren is great, though for sheer size Test + Deca still beats Tren. Tren will not add as much size as Test alone or Test and Deca. Your safer running 1g or even 2g Test pw than you are using 300-400mg Tren pw.
Yes a lot of pros and advanced users swear by tren, though don't beleive everything you hear. If you want quality gains then Tren is good for that, but as i said for sheer mass you want nothing but test, or even better is test and deca. You want to let these compounds aromatise in order to pack on a good amount of size.