I have two fixed magnification illuminated scopes. A Kahles Helia CB 8x50 and a Swarovski 8x56 L NA. The illumination on the Kahles is in the form of a cross whilst the Swarovski is in the form of a dot. I use the Kahles on a 30-06, mainly for Fallow and the Swarovski on a 243, mainly for Roe and Muntjac.
Both have variable intensity of illumination but I only tend to switch them on at very first or last light, usually within or on the edge of a dark woodland background. I have found that they make all the difference in those first or last minutes when one can see the beast but not the centre of the crosshairs. The Swarovski can be adjusted for daytime illumination but the Kahles not so.
They are both discontinued models I believe, althought I bought the Kahles new about three years ago. The Swarovski I bought secondhand from a friend who bought a Z6i. I am very satisfied with them both and could recommend them if available. Light gathering on both is superb as one would expect. If I remember correctly, I paid £630 for the Kahles and £700 for the Swarovski. I felt that they were an excellent buy and good value for money. Good luck, I hope you get what you are looking for.