Rules question - multiwound champions

Champions are still R&F models. In the case of units consisting of multi-wound models, the R&F wounds are basically "pooled."  This pool includes the champion, who, unless targeted and slain by a direct attack, must be the last model to be removed. Indeed, if you kept separate counts for champions, that would mean that you would spread the wounds, reducing the total number of casualties - something that is expressis verbis forbidden. Ruleswise, the champion will "regain" his Wounds with the next round of close combat. Note that this would apply even when he is fighting in a challenge - which some may perhaps find too awkward. 
Of course, if you and your opponent agree etc.

Relevant rules:

BRB p. 45: "Should such a unit suffer wounds, you must remove as many whole models as possible. You are not allowed to spread the wounds throughout the unit to avoid suffering casualties, tempting though it may be to do so.

In this situation, divide the number of wounds caused by the Wounds characteristic of the models in the target unit, removing this number of models from the rear-most rank. Any leftover wounds that were not enough to remove a model are carried over and will be added to the wounds inflicted by any subsequent attacks."

BRB p. 93: "Unless a champion is slain by a direct attack, then he must be the last rank and file model to be removed as a casualty.(...) In essence, wounds inflicted on the unit can overflow onto the champion, but wounds inflicted on the champion cannot overflow onto the unit.

As it happens, I was just re-thinking my position. It depends on how you interpret "overflow" on page 93. Based on the (single wound) example, I initially interpreted this as applying to "excess Wounds," but one could also interpret this as applying to any Wounds.  That does not change anything for single wound models, but in the case of multi-wound models, it would mean that you do not add them to the pool (but also that you would reduce the total number of casualties.)

Champions are a bit of an oddball. Our group always played them as part of the unit wound pool unless they are specifically targeted in melee. If they are targeted, they take wounds as a character. If not, they're the last model removed.