Modified SBS underlayment vs. Conventional tile underlayment

iam new to the site so take it easy. I would like your opinion about using sbs modified tile underlayment vs conventional 15 or 30#?

dont be affraid casperboy,
we can only verbally abuse you here.

sbs is gonna be better than plain dryin, duh.

gweedo.

Mopped on is awesome.

how will the seams be done???what are you using to adhere or attach your sbs to the substrate???

Hello,

I’m going to attach the sheets with mechanical fasteners over osb.
The roof has a 6/12 pitch. I will be installing shingles. The way I figure it as far as price goes, it comes out to about a pizza and a movie for the upgrade from conventional felt. By the way the roof is aprox. 30 sqs.