RE: HHA sights?
I have a optimizer OL-5500
Have had it for 3 seasons now.
Love it, all metal construction, easy adjustability, and when I lost the level bubble earlier this year HHA sent out a replacement to me for no cost. (within a couple days of me contacting them)
The fiber optic pin gathers light well in low light conditions, and when it is bright out, the thing glows like the sun, I do not crawl through the brush, so I cannot say how durable the fiber optics are but (outside of knocking the level off) I have had no problems with mine, and would buy from the company again.