This is getting off topic, but has me curious. A few people now have said 23 as the category for an IPL. I'd like to hear the opinion of some BJCP judges.
My thought is that to be a specialty beer it has to have something that distinguishes it as special from the base style that you can note on the entry form and be tasted and seen by a judge. In a hop forward beer like an IPA, I can't see how anyone would pick out that a lager yeast was used. It's nothing like a Black IPA that has appearance, aroma and flavor differences from a normal IPA. It may be possible to make a cleaner IPA by lagering, but it's more of a point of interest rather than something that effects the overall character of the beer. It seems to me that it would be like decocting your IPA and putting it in 23 for that reason.