... I know Jamil is not sold on it tho.
Some brewers swear by it, others don't like it. I think its worth a few batches for brewers to see themselves. Especially when you are looking for something new to try. The science behind why the hop flavor/aroma stays in the beer may not be as simple as for late hop additions but who cares if it works.
I know that regardless of traditional or FWH,when I use a low alpha hop to get a lot of IBU's, then I get a lot of vegetal material (polyphenols) dissolved in the beer and it comes out grassy and astringent. To me, that makes the bitterness harsh.
You may want to give hop extract (NB sells it as the hop shot, but you can also buy 150g cans for $15 through bulk buys) a try for basic bittering additions. There is no vegetal matter that can lead to the flavors you described above.
The last Pilsners I made used 30g Saazer as FWH and 2 g hop extract (54% AA) for bittering. This is for 25 l preboil. I feel that the utilization for hop extract is a bit less than for hop pellets and you have to add a bit more.