Thanks everyone for all the replies.
Sounds like I need more attention to structuring, in addition to some better wax. Having worked in a shop, we always tried to leave the "as ground" surface intact, so it looks good. Another consequence of serving "Joe the skier" who just wants a shiny finish from their expensive tune, and doesn't know any better, and probably can't tell the difference anyway. This can be the downside of working in a shop...all the "general population" skiers can make you think the details don't matter much (except with bindings of course).
But from what folks have said here, and what I've read elsewhere, a higher structure is probably better for spring snow.
Another source suggested using sandpaper to structure bases. That sounds more aggressive than a brass or nylon brush, but if roughening the base is the idea, seems like that would certainly work. Does anyone here structure with sandpaper? I assume after doing this for spring, you start next season with a fresh base grind? I suppose most serious skiers probably would anyway.
I'll also get some wax. I'd been looking at Hertel, and was impressed that they took the time to post helpful videos on their web site, so I think I'll try some Spring Solution on my newly structured bases...
How do shops structure bases? As I recall (been a decade+), the stone grinder has a "dressing diamond" that is used to square up the wheel and refresh the abrasive surface. Do you speed up the dresser to get a rougher grinding wheel face? Or do you stick with a normal grind then structure with brush/sandpaper by hand? I don't have a stone grinder, but this may help decide if I should spend extra if there's "machine structure" option...