buying dillema precision 3591 portability and linux hybrid

I'm contemplating my next work laptop, and considering the Precision 3591

I will be running linux on it. 

My current laptop is Latitude 7650 and I wanted to improve screen brightness and get a full keyboard while maintianing 64GB ram.

My concerns with the precision, If I opt for the larger battery to get reasonable battery life, how much heavier will this be? If I max it out will it still be sub 2Kg? 

How well does hybrid graphic work on Linux, the better graphics are in my opinion nice to have, but if I pay in battery life and weight for not so functioning graphics that is in an issue. 

Can anyone advise?