Thats a whole can of worms. I believe it helps add head retention, while some studies suggest not. It is a dextrine malt so it should in theory give better body, mouth feel, head and lacing. Some people say it doesn't work, some do. I believe it helps and it certainly doesn't detract from the beer so I just go with it.
I don't mind David heaths recipes, but usually find them crystal malt inclined. I prefer a biscuit note to a sweet caramel note personally. A true pils should really be decocted (or use melanoidin malt) but I find biscuit about 2% and munich about 10% gives a nice malt character, in conjunction with the bohemian floor malted pilsner I use. Standard pilsner malt is perfectly fine, I just like the boho stuff.
Heard good things about Oslo, it won't give the same crispness of a true Pils, and even my tried and true recipe done with W34-70 instead of my Czech Lager (bud) yeast got a look from the wife and a "it's not as clean as usual, tastes a bit green" without knowing it was 34-70 at 21c on a quick turn for a Christmas party. Still spent 3 weeks in the keg and a week in ferment but alas she was right. Wasn't the same. It was close, but even pressure fermenting hot won't get exactly there with lager yeast. My opinion anyway, and I love pressure fermenting
