The Crumble Factor: homemade bars will always have some degree of crumble (they don't contain the binders/fillers that manufactured commercials bars do), but the date paste is helpful for adhesion and minimizing crumble.
Date Paste: I purchased a 16 oz date paste by Royal Palm (no sugar added) on Amazon. You could also use pitted dates to create the paste (with same softening/blending procedure set out in recipe).
Substitutions & Deletions: you can substitute any nut/seed of choice (or nut/seed butter) or dried fruit (ex: sliced dried apricot, dried cranberry, dried blueberry, raisin, fig, etc) or freeze dried strawberries instead of raspberries. However if you remove ingredient classes without replacing them, (or change the wet/dry ratio), these bars will not work in the same way.
Freeze Dried Berries: I purchased the freeze dried raspberries at Whole Foods (1 oz bag/365 brand).
You don't have to top with berries: the berries are fun, colorful and tasty, but you can omit them and the bars will still work great!
Oats & Gluten: oats by nature are gluten free however many commercially sold oats do contain gluten due to cross-contamination issues. Be sure to seek out certified gluten-free oats, as required.
Sodium: I used salted pumpkin seeds and salted whole almonds; I mention it because it does add some flavor to the bars.
Storage: these bars don't do as well outside the freezer but you could use travelling/lunchbox ice packs to keep them together somewhat.