It's only about a pound heavier. Not that much. And the extra weight is justified due to its more robust construction. You can bang zombie's heads all day long, which you can't probably do with the RDB. LOL
Regarding the trigger, we haven't really tried it and compared it with the ARs or the RDBs. So, I'll reserve judgement on that. Do you expect it to be much worse than the RDBs? I don't expect it to be. Most early reviews indicate that it is satisfactory; not the best but not that bad either. Which bullpup trigger do you consider the best? All bullpup triggers will be expected to be worse than the ARs. That's just the nature of the beast. Yes, 3rd party trigger updates are welcome and it won't be long before somebody comes up with it. In fact, I won't be surprised if somebody did before the start of the spring or summer shooting season.
Comparing an aspect of the Hellion to some random aspect of some rifle (ie Garand) is silly. You can always find something that another rifle is superior in. That is not the point. The goal is the overall package. What are those set of qualities that satisfy most of your needs and wants. The Hellion checks the most number of boxes for me. Maybe it does not for you since you have a different set of needs and wants.
And believe you me, the looks and aesthetics while important is not on the top of the list. Why? do you really have the impression that I am that naïve to make looks the primary priority for my SHTF rifle? Before looking at the BR-18 and the RDB, I was considering the Chinese QBZ-97 rifle. And that is one ugly rifle but it has Military Creds.
You may be more informed in this, so tell me which commercial ARs are "direct" adaptation of a military rifle? In other words, it is the actual military rifle with only minor changes made from its military version. The Hellion is one such rifle. Tell me which commercial, civilian ARs are like that and I'll look at it and compare.