Theoretically, R2R DACs are more analog sounding and less detailed than their delta-sigma counterparts. This is driven by some of the more popular R2R DACs sound profile. It is not universally true as I have heard some miserably bright R2Rs and some that can rival any delta-sigma in terms of detail.
The actual tech is not of huge importance and the implementation of the resistor ladder or chips and the output stage dictate the sound and refinement levels of the DAC.
If you are looking for a warmer sounding unit that will give you good detail and a big soundstage I would look at the Border Patrol you mention above and the Questyle CMA 12. I know it is more headphone oriented but it is not bright and works wonderfully as a standalone DAC.
The Border Patrol might sound a hair more "raw" as it is NOS while the Questyle will be a bit more refined.
Good luck