HG often has 20% off sales. The incubator gives a choice of fabric weights, temperature ratings, and lengths. Remember, it doesn't have to run the full length of the hammock; it has to run the full length of you. With those combinations, you can configure one pretty light if you are on the short side, and at least equal, if not better, than others if you are "standard" size.
Overstuff mostly keeps the down from shifting a bit. It's the loft that influences the temperature rating, and HG recommends getting a different temperature rating - if that's your concern - instead of overstuffing. That's because the underquilts are cut to allow for different loft.
The overstuff can be a plus or minus. Not having the down fill shift sounds good, but it still starts to cluster after some use. Being able to shake it easily into the location you want is a plus for some people. When I started, I bought my quilts with 2 oz overstuff - the most HG recommends if you are going to do it at all. It was probably unnecessary.
HG has made my primary quilts. I have a few others I've picked up used, and different vendors have their fans. Though a higher "Fill", like 900 or 950, sounds good, the performance difference might not be worth the extra coin.
And the environment (i.e. humidity) you plan to adventure in plays a part. An internet search will point out some of the Cons, but the summary is, "For most hammock campers, 800 FP hits the sweet spot of weight, warmth, durability, and cost."