I've not used it yet, but because I like lightweight rifles, I've been looking real hard at the Midwest Industries Gen2 handguard with T1 direct-mount top cover. However, my gun budget just went to zero because of kung flu.
https://www.midwestindustriesinc.com...-akg2-umt1.htm
It's only 7.5 oz without an optic. I don't think it would heat up quite as fast as the Ultimak, which may or may not matter to you. You also gain the ability to mount a light via M-lok, so that makes it a nice all-in-one solution if you want a micro-dot sight, light, and sling mount (it has integrated qd sling sockets). You can also order the top section for other optic footprints, but I'm not sure which others will let you used the irons through the optic. I believe you can do so with the T1 and varients/clones. Military Arms YouTube channel has done a review. https://www.youtube.com/watch?v=s8W0HuHKBOQ
I think RS Regulate has some high quality side rail mount options if you want to go that direction. A P-F member affiliated with their company posted in this thread above ^