Hey, just wanted to follow up.
I ordered my P.Exo lid today for my XL300. There are a bit more "fees" for our tanks (also XL200 and a couple others). We apparently have "armored seams" on the front which require additional cuts. Also, our overflow box sits higher which requires a large cutout. Each of these add a little bit of $ to the order.
However, with that being said, it seems as though they have our tanks figured out and the ordering process was very smooth so far. I am sure they will contact me for more info once they are ready. Up to now, easy breezy.
I just wanted to give you a heads up about the process and hope that you don't get hit by sticker shock from the additional cuts.