stout, steep or mash dark grains?

I need opinions on which to do. I converted the below recipe to all grain and wanted to know which would be best. My gut tells me to mash all grains including the dark grains with the rest however I did read that some people steep those seperately like you would while brewing with extract. My concern was making the wort too bitter. I haven't brewed a Stout with AG before so all guidance is welcome.

https://www.homebrewtalk.com/f68/macmanus-irish-stout-254019/

The typical way is to mix all the grains together and mash. The bitterness comes from the type and quantity of grain and the type and quantity and time of boiling for the hops.

I always mash all my grains together in a stout.

The reason for adding the roasted grains later (like only during the sparge) is if you want to extract color but not much flavor from the darker grains. That might be if you were making a Black IPA, say, or using some roasted barley for color in an amber but didn't want a roasty flavor.

Since this IS a stout after all, I would think you'd want the flavor of those "stout" grains and I would mash it all together.

Thanks, that's what I was planning on doing but after reading more about it found many different opinions and variations.

beerloaf