The Cuisinart 4-Cup Mini Prep is great for simple light-weight jobs like making salad dressing and chopping onions, but when I use it with heavier foods (like cooked spinach) I can smell the motor burning. So to avoid motor burnout, I no longer use the Mini Prep to process even small quantities of high-density foods - a use limitation I hadn't anticipated.
Regarding capacity, keep in mind that although the total volume held by the work bowl is 4 cups, you really can't work in batches much over 2 cups (less for dry items). If you exceed the batch limit, you'll end up with a result that is over processed on the bottom and untouched on the top. The user manual also advises that to avoid motor strain, the work bowl should never be filled more than two-thirds the way up the blade assembly column. So in practice, the 4-cup work bowl translates to a best-case maximum of 2 cups end product.
I'd also like to point out that the motor casing for the Cuisinart Mini Prep listed here (model DLC-4CHB) is plastic with a faux stainless steel finish. When I bought this product, I inferred from the item title that the casing was constructed of stainless steel. But if you look closely at the detailed item description, you'll see (as I discovered only after purchase!) that the construction is plastic made to look like stainless steel. And the plastic is pretty flimsy at that, so just be aware of what you are buying.
Bottom line: Would I buy this Mini Prep again? Probably not. For my needs, I think I'd look for something sturdier and more versatile. Do I think the Mini Prep is a complete train wreck? No, I use it for what it's worth at least 4 times a week and I appreciate how easy it is to clean. The important thing is to have a firm idea of how you want to use the Mini Prep prior to purchasing one. Want small batches of pesto, salsa or chopped onion? You're good to go. Want to make smoothies or process heavy and dense foods? You'll need to look for something with greater capacity and a stronger motor.
One final note on a lesson I learned the hard way...if when using the Mini Prep you consistently end up with onions that are pureed not chopped or nuts that are pulverized to dust, try alternating pulses between the Chop and Grind buttons. Alternating the two buttons moves the food around the work bowl for a more even result.