What real difference does the lsa on a cam make?

Generally, a tight LSA will result in more PEAK HP and TQ, while a wider LSA will result in a little lower number for both, BUT also offer a much broader HP and TQ curve. Generally, with a street driven car, you will want some width to the LSA. Comp settled on 110 pretty much across the board and although sometimes I make fun of it and call it "cookie cutter" it's actually a very good compromise. I discount everything about idle quality, because for me, what's important is how it effects the way the engine RUNS, not SOUNDS. Also too, duration @ .050 has an effect on everything too. It all pretty much boils down to what you want to do.