I think this is a pretty interesting topic. I definitely find differences from one maltster to another, sometimes those differences are subtle, sometimes they can be quite pronounced.
But if I'm dreaming up a recipe and have a goal in mind, I don't want those differences getting in my way...and so I've pretty much settled on using one maltster only. I've become very familiar with these grains and what they can and cannot bring to the beer and I find this repeatability helps me get close to what I'm after. I know the sweet, hay character I'll get from their Pils malt, the nuttiness from the Munich, the foam boosting quality from the Spelt...etc.
But I've also learned that they have no substitute for Maris Otter (who does?) and they also can't replicate the sweetness I get from British Crystal malts. (In fact, I don't believe US and UK crystal malts should ever be interchanged, but that's not really saying anything groundbreaking.)
Anyway, that's the long way of saying what everyone above has already said. I wouldn't expect one maltster's Pale or Pils or Roasted Barley to replace another's, though they might get you close. Or not. Brew and take good notes. And certainly, record what brand malt you are using.