Hah, no problem. The other day I had to get out a sheet of paper and write all the classes down, because I couldn't remember how many there were myself.
Heck, I've been in the middle of games and had to open up the menu to figure out which classes weren't currently being played. It's hard to keep track of all of them.
On another note, Shadoo's mention of a literal "jack of all trades" Un-perked / Perkless class is interesting...
After I graduated from Normal difficulty to consistently playing Hard, and had all my perks high enough that the bonuses were REALLY noticeable, I started to look back and miss being able to carry cross-class weapons and it not matter much..
So I'd welcome a neutral perk that can carry multiple class' weapons with them and be equally good with them all.. preferably with a specific class benefit or optional upgrade for increased max loadout (if KF2 still uses a weight-based system and not a Primary/Secondary slot system?) Maybe an optional upgrade for faster weapon-swapping?
Alternatively... Optional Upgrades in certain perks that benefit weapons non-standard to them. Lite-hybridization, if you will.