you would need the tighter LSA for an engine that you can't easily get the CR high enough on. Tighter LSA "is like" higher compression. Whis results in better throttle response and more power, higher efficiency. Until you go too far and have knock issues.
Wider LSA reduces compression and generally the valve overlap, so less compression or mixture is bled through the exhaust, so it's better for turbo applications. But it makes an engine lazy down low and a big cam withwide LSA and not enough compression, would be a pig to drive until it gets "on cam". Which is the #1 reason people are afraid of big cams. You have to give them compression.
BUT it's not quite as simple as that, there are other factors that affect the outcome. Like Overlap. It is not directly linear or directly linked to LSA.
If you can't get your compression ratio high enough, you need to make compression with a cam that doesn't bleed compression out.
