Is the readout hard to see, or the actual image? A red readout will be easier to see than a black one, against a dark background. If the image is too dark, you want to look for one with a larger exit pupil and higher light transmission.
The problem is, most rangefinders have a small exit pupil, and light transmission under 80% due to the complexity of having electronics in the optical system. Even the best rangefinding binoculars will have a few percent less light transmission in the barrel that houses the electronics. Leica's solution to this was to use perger porro prisms in their alpha rangefinding binoculars, which in theory should allow for higher light transmission than traditional SP-roof prisms. Some users on birdforum actually use the 8x42 Geovid 3200.com for birding, and just ignore the rangefinding capabilities, because they prefer it optically to Noctivid, EL, NL, SF, etc. Probably overkill for what you're looking for, but if you're in the market for new binos you could kill 2 birds with 1 stone.
I have a Leica rangefinder, I think it's a 7x24. It's about as good in low-light as you would would expect from an optic with a small exit pupil and transmission around 80%... It's useable enough until the end of shooting light most of the time, but switching to my 7x42 binoculars is like turning on a light switch.
