The wording is absolutely horrible. What the rules actually say when it comes to first aid is this:
1. Threshold is (2)
2. You heal a box of damage for each net hit over the threshold (hits - 2)
3. The maximum damage that can be healed is equal to the skill rating being used.
4. First aid must be applied within 12 hours of the damage.
5. First aid can only be used once for a set of wounds.
Now then, the medkit can work in three different ways:
Case A). Trained characters (First Aid 1 or higher) may add the the first aid kit's rating to their dice as a modifier.
Case B). Untrained characters (First Aid at 0) use the device rating in place of their skill.
Case C). The Medkit can be left hooked up to a target and rolls only its device rating for the test.
Now this actually means it works three different ways ruleswise (I said it was worded horribly right). To break it down fully.
Case A). The device rating is not used as a skill but as a modifier. This means you get +Device Rating to your roll, but you're still capped at healing a number of wounds equal to your skill rating (point 3). This may not seem like much, but considering that you need 3 hits to heal one box (Points 1 and 2) which is an average of nine dice, its not a bad investment to take a first aid kits. Afterall a rating 6 kit only adds 2 hits on average which given an average attribute of 3 and a proficient skill 3 would still mean you won't cap out your healing ability on average. Keep in mind that first aid can only be used once, so usually the highest skill level character should be doing it (unless they have racked up the penalties).
Case B). The wording can be taken two ways. First it can be taken to mean that the players skill is treated as the device rating in which case the player is capped at healing a number of wounds equal to the device rating (point 3). Keep in mind that this requires a number of hits equal to device rating+2 which is unlikely to occur unskilled. The second way is that the character uses the medkit as their skill dice (but not in every respect) which would mean that the hero cannot actually heal any wounds (0 skill combined with point 3).
Case C). The medkit uses its device rating for its skill and can heal a maximum number of boxes equal to its device rating (point 3). Keep in mind that this is impossible since it only rolls a number of dice equal to it's device rating and even with all hits it will only heal a number of boxes equal to hits - 2 (Point 1 and 2).
In summary, I think medkits should replace the cap but I can't find a ruling where they actually do.
