Another thing to consider is that using a single type-list with over 100 message types will significantly (to me) slow compile time and may approach compiler limits.
I was worrying about this.
See Appendix C of "C++ Template Metaprogramming" by Abrahams and Gurtovoy. Choosing the proper MPL collection can make the difference. None of the effects mentioned in the chapter shows a wall near N=100. --John TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.