I don't think transposing into the KID is a surprise weapon for anyone using the Pirc :) If anything it is even a little less scary for me :) The BENEFIT of no c4 in the Pirc is that it is one fewer wasted tempo and you can bring pieces into the attack more quickly.
Maybe I am wrong?
Well for one there is a lot of theory associated with the Kings indian defense that differs slightly (but significantly) from that of the Pirc. So if the Pirc player does not know theory in KID the white player transposing may have a significant advantage. Also, i particularly enjoy playing the samish line in the kings indian defense from white's perspective.
We were discussing these sorts of things 30 years ago when I was playing these lines, so nothing new in the sun that early... and I recall seeing a discussion of this by Tartakower in the 1940s..... an old Wiener Schachzeitung.
RESIDENT PIRC FANATIC REPORTING IN!
e4 - d6 - c4 is an interesting play, and you are not the first to have tried it. I generally use an anti KID move, e5 (c5 is also possible, but I always end up with some terrible variation of the sicilian...)
I prefer e5, as white moves tend to be restricted. d3?! runs into inferior variations of the KID, and Nf3 runs into an inferior variation of the philidors (c4 is a good square for the bishop to boot...). I only know of one line that doesn't run into these inferior variations, g3, but I doubt its sound However, I'm not sure.
If you want to force your opponent into KID lines, you can also try 1.e4 d6 2.d4 Nf6 3.f3. This often goes into a Sämisch (although other lines can again be forced)
I'm not sure if this is new or not...but I thought of it on the way to class. This is a line against the pirc that transposes straight into the KID. The problem is that after 1. e4 d6 2.d4 Nf6 3. f3 black can play d5! and get a different sort of game than what i want to play. My idea is to play 1. e4 d6 and now 2.c4! The idea is that if 2...Nf6 3. Nc3 g6 4. d4 (transposing into the KID). If 2...Nf6 3. Nc3 e5 then i can play 4. Nf3 and transpose to KID main line. And finally if 3... c5 i can transpose to maracozy bind or the botvonik system.
Thanks for the help!