I own a modified DL3 but have limited exposure to the Benchmark. From what I remember I'd say the Benchmark has a slightly less detailed stage than the stock DL3. In a noisy room (I have wood floors), the stock DL3 came across as having a touch of glare (hence my mod), but I have no evidence that says the Benchmark wouldn't have had the same issue. From everything I've read and encountered, the two are fairly similar in most respects with the DL3 getting the nod for detail and the Benchmark giving you a headphone amp and volume attenuation.
I don't think you can go wrong with either. And, since I believe both have 30 day trial periods, nothing wrong with bringing both home and keeping the one you like best.
However, if you like PS Audio products (like I do), their next generation DAC comes out early next year. I previewed it at the RMAF last month and it has potential to be a real game changer with support for every resolution you can dream of, I2S data interface (no transport jitter!!), expandable architecture, and a damn sexy look. Tentative price point is $2,000