One of the issues with kits was the special ability and hindrance that went with each one. The base class had no explicitly stated hindrances, yet the "flavor" version of the base class had a boon and a bane that somehow balanced out.
One example of this was the swashbuckler kit. The three special bonus were an AC bonus (because he's so hard to hit!), Rogue non-weapon proficiencies at half price, and a +2 adjustment to the reaction roll in some situations. To balance this out was a hindrance that stated that the swashbuckler was a trouble magnet.
The purpose behind the first two bonuses was to force a swashbuckler PC to take unpopular, but genre-correct weapons and non-weapon proficiencies. I understand the rationale, but forcing a character to take weapons feels like the wrong way to go about it.
I would recommend simply that a swashbuckler keeps the weapon specialization (just like any other warrior) but is required to take the tumbling non-weapon proficiency. Then I'd recommend the seafaring, blind fighting and tightrope walking non-weapon proficiencies.
Disguise, forgery and the like sound more like a thief. Instead of creating a kit with a fighter that wants to be a thief-acrobat, I'd create a buccaneer kit for Rogues that provide the appropriate weapons (black powder pistol, sabre, rapier, etc) and the non-weapon proficiencies for being a rope-walking cheat. Specifically, include the gaming, disguise, and forgery non-weapon proficiencies for the buccaneer while including pick pockets, read languages, etc. With the extra non-weapon proficiencies that Rogues get in my retroclone, the buccaneer will have everything he/she needs to sail the seven seas and charm his/her way through settled lands and territories.
The point is that both the swashbuckler kit and the buccaneer kits do not provide special abilities and can be created using the rules of the base class.
Let's take another example, the priest-monk kit.
Making the monk a subset of the priest is interesting. However, I would think that a wizard kit that featured a weapon proficiency in martial arts would be more interesting. Make the somatic components of spells a type of maneuver and there's a lot of interesting stuff you can do without bending the rules.
Honestly, though, I'd make the monk a different class - they would have the martial arts weapon proficiency, but I'd also give them a special ability that provides level-based bonuses to AC. Having a new special ability necessitates the creation of another class, otherwise the balance issues come back with a vengeance.
So what will kits look like? There will be five or six kits of each of the four main classes. The kits may provide a bonus non-wepaon proficiency, but otherwise must follow the rules of creating a character in the man dlass.
wilderness warrior (for all types of terrain, including urban)
More later as time warrants.