I spent some time and went through the national regional qualifiers list from 2008 and seperated it into runners for the new east region and the new west region. Then I counted through and found the 48th qualifier from each region (24th for relays, and noted when there weren't 48 total from a region on the 08 regional list). I've only completed the women so far but here is what I found...
100: E-11.71 W-11.73
200: E-23.90 W-23.91
400: E-54.30 W-54.61
800: E-2:09.36 W-2:08.98
1500: E-4:27.37 W-4:26.84
Steeple: E-Only 43 qualifiers @ 10:48.79 W-10:38.44
5k: E-16:45.62 W-16:46.96
10k: E-Only 23 @ 34:53.01 W-Only 23 @ 34:57.21
100H: E-13.68 W-13.81
400H: 60.30 W-Only 40 @ 60.81
4x1: E-45.4 W-45.67
4x4: E-3:40.75 W-3:41.20
HJ: E-Only 36 @ 1.75 W-Only 38 @ 1.75
PV: W-3.85 E-Only 37 @ 3.85
LJ: E-6.04 W-6.02
TJ: E-12.41 W-12.43
SP: E-14.59 W-14.57
DT: E-46.92 W-47.52
HT: E-Only 39 54.35 W-54.35
JT: E-Only 39 43.45 W-44.09
Men to come later. Will probably look more in depth to a few aspects as well.
I agree that I think the biggest concern with the new system is 48 pole vaulters at one competition.
I think one of the main reasons for not including the multi events is because they are a huge drain on a facility. If you've got them throwing, vaulting, etc. you can't have the actual throwers, vaulters, etc. doing so and with these many numbers it almost becomes impossible.