Thanks all, for the feedback!
@surfandski, I'm a new zipfit owner, too. Skied them all of this past season, and they were great. But there's just not enough OMFit material back there in the heel to make an appreciable difference when confronted with my heel spurs. Hopefully molding and/or a highly localized punch can accommodate my spurs. Sounds like it may from all the other comments. Now I just need to find a shop that carries the XTD for next season. May have to travel up to Tahoe for a boofitting day, as it's somewhat slim pickings for touring-specific equipment here in the south Bay Area.
Which Zipfits did you get? I ended up with the Grand Prix and I plan to harvest some OMfit out of one on my much larger bad ankle and then I'll have some extra OMfit for touch up down the road once things pack in. Your heel spur looks substantial so it sounds like you're on the right track with a punch. I'm sure Start Haus or other shops could hook you up with whatever you need. I lived in Truckee and S. Tahoe growing up and that's certainly not a bad trip from the Bay. Good luck with the spur!