JimmyP
It’s going to be difficult to say definitively a deep puck is better than a shallow one. You have to consider the quality of the grinder - a shallow puck will require a finer grind - flow rate, ratio, pre-infusion, light or dark roast/density of the coffee, baskets holes clogging, silt in the cup, puck erosion, puck prep and likelihood of channelling.
IMS produced 58mm baskets a few years ago designed for single shots. They are bowl-shaped and only have holes in the middle - they are supposed to produce single shots that aren’t lacking in body. The shots I got from them were certainly different to the 18g VST - more clarity, more acidity, slightly less body. They weren’t the same as a double shot from a larger basket only smaller, which is what was really advertised, but they came close. The pucks were very thin compared to the VST.
I’ve been using the 49mm IMS fine mesh basket for the past few days. It just about fits a 14g dose and puck screen. It’s a tight fit and I think 13g or 12g might be better with the screen. The shots are very clear and have acidity and body similar to the IMS “the single” baskets which took a 12g dose.