Are high-end cone grinders adjustable? I switched from a modestly priced blade grinder to a moderately priced cone grinder because the results were inconsistent  (some very fine powder and some only fragmented beans mixed with usable grounds).

Will I have more consistency and control if I switch to a high-end cone grinder? I'm thinking about a refurbished restaurant grade grinder, not an industrial grade machine as one might find at a Starbucks or boutique roaster.
Yes, high end grinders are generally adjustable. Some even have macro and micro adjustments. For example the Baratza Vario grinder 

Hand grinders are also adjustable, and provide a good grind. See the Hario range

The larger commercial grinders are sometimes aimed more at bulk output than at a precise and consistent grind. They grind the coffee very quickly, which may not be the quality you are looking for. Some people prefer grinders that operate at a lower speed so that the temperature of the burrs stays low, reducing the chance of the grind getting over roasted

Here's a list of mid to high end grinders. You will notice that they all have adjustments.