The difference between the 30 and 90 is nil until you get past 5 deg of yaw. At high yaw most people will have handling issues with the deep rims. The bottom line as I’ve been saying for 15 years is that a decently shaped 25-30mm aluminum-rimmed wheel with minimal aero spokes is an aero wheel. The gains to be had going deeper are minimal, and usually a poor speed/$ ratio.
For the OP’s question regarding road racing in a pack, I see no reason to go past 40-50mm and only got that deep if you think you will go solo or in a small break. An aero frame, helmet, and skinsuit will yield bigger gains without the potential handling problems.
