With new tier design, I'd really like to see an end to the "stronger teams get weaker tiers" problem. For example, If four players with levels 5,6,8,9 want to play a tier 5-9 scenario, they have to play the low subtier. If a level 5 character joins them, they now have to play the high subtier. Add another level 5 character, and they're back to the low subtier.
This is weird. Adding to your team should never reduce the subtier difficulty and losing a team member should never increase the subtier difficulty. The reason for this is average party level. Since a level 7 character is (by CR/XP guidelines) as powerful as two level 5 characters, they should be treated as such.
My suggested solution is to use relative powers based on the XP system. If you're the minimum level needed for a scenario, you're 2 points. One level higher is 3 points, a level after that is 4, the next is 6, then 8. Then, set thresholds based on total party points: 4-player low tier for up to 12 points, 6-player low tier for 13 to 22 points, 4-player high tier for 23 to 32 points, and 6-player high tier for 33+ points. The above example (levels 5,6,8,9) is a 2+3+6+8=19-point party, so it gets you the low tier for 6 players. Adding a 5th-level player (21 points) now just keeps you at the low subtier, but adding a final 5th-level player (23 points) now pushes your party into the 4-player high subtier.
Most parties remain unchanged under this system, but you never get a tougher subtier for losing a party member.
