OK, first off an open pollination means he used multiple males and females from his F2 generation.
Secondly, you should totally buy some BCSC Northern Lights I hear they have a great website. B got his back when BCSC was actually worthwhile back in '95 or '96.
Thirdly, the original NL#5 was a clone, hence the #5, and so the original seed releases were crosses between a male in the stock of the seed company and the original #5 clone (supposedly) and then either bx'd or not to the NL#5 clone. BCSC's NL#5 was in no way an actual true breeding 7+ generation IBL when they came on the scene. I've grown maybe 20-24 females of NL#5 and NL#1 varieties from different seed companies or from clone over the past decade, and there's always been at least two phenotypes and two chemotypes in every NL seed grow I've done. Pole plants and christmas trees; and usually piney/menthol and then depending on the breeder either citrus or incense. It's not like you're going to run them and come up with a 14 week 4x stretch haze, but my direct experience with Northern Lights has been that the ones with more afghani influence, i.e. the shorter and faster finishing varieties, tend to be lower yielding and have a more one dimensional stone; consequently while they might be better suited to SOG growers or people growing purely for speed, I prefer ones that are bigger and a little take a little longer in exchange for a heftier per plant yield and a more blueberry-like high.
I've never worked with Peak Seeds NL, but it is also worked out from the original mid nineties BCSC Northern Lights #5; and I've heard it is one of if not the best NL representations on the market.
Lastly, have you done a lot of f2 and f3 crosses? I've always found that in order for an f3 generation to have more variation than an f2 you have to intentionally breed it into the f3, and if you have more undesirable phenotypes in your f3 than f2 that means that you had a problem with your selection for parents. I have a good deal of confidence in B's ability to select desirable parents, more than in any other breeder working today.