Nathan Welcome on our forum.
Generally Dulens are classic lens designs re-calculated with computer to be close to apochromatic, so barely no chromatic abberations even wide open. Breathing is moderate. As you might know most of the OKC lomo lenses have very well controlled breathing, next to nothing.
A good set would be: 5-18-1, 3-22-1, 7-28-1, 11-35-1, 1-40-1, 1-50-6, 6-75-1, 2-100-2, And rehousing are expensive but if you buy them in kinor versions they can be quite nicely serviced apart from of course the rotating front and extending barrel. The brass version you have is a lenikap made for sync sound cameras, you can simply pull out the optical block which weights only a few grams and rehouse it in something else, or find a other copy (these are quite easy to find). Lomos are vintage, and in my opinion the best vintage lenses, not vintage because they are jerky, but very balanced, low breathing, very consistent colour cast and contrast, high iris blade count, high micro contast and reasonable sharp, very paintery lenses, with a lot of added warmt, and beautiful bokeh, and bell curve focus fall off.
DUlens are basically modern lenses, very well designed mechanics, and the smallest cine lenses for large format I know of, very sharp wide open, but modern rendering with a touch, the coating is not everyones taste, can flare heavily with pronounced rainbows. We will soon sell these lenses, but for now its impossible to stock these but shortly after the summer we will start doing so. (Send us an email for pre-order)
In our opinion the leica r are the most overrated lenses together withcanon fd. very mediocre, and always a mixed bag, impossible to compile a reasonable matching set.
The leica m are fun, but on digital the wider ones will smear in the corners due to olpdf and non telecentric lens design.
Hope this helps.
Conclusion : dulens vs lomo is apples and p… we can make you a quick side by side next week with the 31mm dulens and the 7-28 and 11-35 lomo lens ( or 12-35 or 15-35,)