I would like to share my impressions in internet-blitz-games with a line mentioned in the book, the KI-classical with f3 and g4
(1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 O-O 6.Be2 e5 7.O-O Nc6 8.d5 Ne7 9.Ne1 Nd7/e8 10.f3 f5 11.g4)
What I did is reading the chapter (not at all learning the line), trying to remember the plans, and playing it in blitz games. This is what I usually do to test a line that is a candidate for "repertoire-change".
The idea simply is to get to know wether I "feel" the position or not.
Afterwards I asked serveral opponents if they liked that line or not
Currently the number of games may be about 50, so it it limited, but I guess not worthless. The opponents were rated between 1900 and about 2250 at the server.
- Lower rated players and those that didn't know the line usually either played
- 11...f4 without closing the queenside (with lets say ...c5) which IMHO more or less automatically leads to a white win
- 11...fxg4 after which the usual kingside counterplay more or less is gone. Those games had a higher percentage of draws due to the fact that there is just one open file, where sometimes the heavy artillery was exchanged. Whites risk to lose the game in that line IMHO is about zero. He plays with a secure draw in hands with a slight advantage for a win.
The higher rated player sometimes outplayed me due to my lacking theoretical knowledge, especially in the line with 11...Kh8.
More or less everybody (who answered me) said that he / she disliked the resulting positions (Because they are "boring" and similar stuff

).
All this convinces me that the line is a good idea for positional players to incorporate them into their repertoire.
'Boring' often equals 'I don't understand the complexities of the position...so will shuffle about and lose'
Particularly with lower rated players. Hence 'c3 sicilian is boring' and another one chalked up.
Yeah, havent looked at g4 properly for nearly 20 years, but its a worthy line.