I may be able to shed some light on your decision. I have moderately bad night vision. Probably much better than yours, from the sounds of it, but much worse than almost everyone around me. Bad enough that car high-beams don't cut if for me and I've got 400W of rally-style lights on my car so I can drive at night without being tense about the fact that I can't see. We just started riding at night due to the heat and the fact that she doesn't get off work until a time that will see us riding after dark most of the year. We bought two lights:

A Romisen RC-N3 II R4

and

A Fenix LD20+ Premium R4

We paid about $30 for the Romisen and about $60 for the Fenix. I can honestly say I can see why the Fenix costs more. First of all, for me, they would both be adequate "emergency" or backup lights. Riding sufficiently slowly (say 10mph), I can pick my way through any path with either of them. They're not bright enough for me to say "Oh, man, I can see perfectly well and there's no stress at all!" but they're bright enough that I would definitely make it home safely. However, the Romisen on High is only as bright as the Fenix on High but the Fenix has this mode called Turbo. Turbo is considerably brighter. With the Fenix on Turbo, I can ride at full pace uphill and on the flat. Downhill, the Fenix still isn't bright enough for me to go full speed. Additionally, the Fenix is easier to switch between modes, you can feel it's better put together, and, comparing High to High, MUCH better on batteries than the Romisen. The Fenix has also been proved to be quite waterproof. The beam from both lights is quite nice and totally useful for riding paths and the like.

So I guess the summary is that, with my moderately bad night vision, the Romisen would get my home safely but I'd be conscious of the fact I can't see as well as I want.. The Fenix would also get me home safely and would allow me to go faster, and I'd feel more comfortable relying on it, but I'd still be wishing for more light. But for the long term, I'm looking for something even brighter so I can ride full-speed in all conditions without feeling nervous about the lack of light.