Irwin was around a decade ago, closed, then reopened a couple of years ago. They advertise 1,000+ acres, which is very small for a snowcat operation.
With regard to the snow, 2 years is far from enough to make official claims. I have run this by Knox Williams, head of Colorado Avalanche Information Center for over 30 years. He says Kebler Pass near Irwin is the 2nd snowiest spot in Colorado, behind Buffalo Pass and ahead of Wolf Creek. 450 inches November-April might be a good guess as Wolf Creek is 396 and Buffalo Pass by water content is similar to Alta. 600 is a rare number verifiably achieved only by Mt. Baker (647) and the top elevation at Alyeska (632) with Niseko (572) within shouting distance. For interior locations with drier snow, 27 months at Mt. Copeland in British Columbia, indexed to long term data at Mt. Fidelity, project to an average of 596. 25 months at Mustang's lodge project to 550. The locations are fairly close to each other in the Monashees, which do have the reputation of the most snow in interior B.C. For actual long term data Alta is 534.