I was looking at the Mariposa, and was concerned about durability as hillwalking in the UK and Northern Europe involves a real need for durability or the need to be really careful with your pack. I did not want to have to be worried about whether my pack might get punctured at any moment when scrambling so went for the more durable but still very lightweight Gorilla. Thus, as some have already said, the Gorilla is popular because of that fact. Also, I really do not need to space that the Mariposa has to offer and a slightly smaller sack will carry better than a lightly loaded bigger one.

for a shelter look at:

Big agnes fly creek 2 UL
Tarptents or the spinn versions at gossamer gear
Lightheart tents
Sixmoon desings tents

under 3lbs for sure on these.

also i went for a framed pack to frameless and its introduction hike was 100 miles and I felt great the first day back. that never had happened before.

@Benjamin
"Re bugs, I don't think the tent will help much against ticks, since you typically get ticks on you by brushing against bushes on the trail. "

On the contrary, in the OP's region there are areas where ticks descend upon you in horrifying numbers, especially mid-summer to fall. This I find especially true on trails shared with equestrians. I have been covered in ticks more than twice and will never sleep in this region without a noseeum shield. Some of the ticks are so teeny they look like little freckles and you don't know they are on you until you get home. I have many scars from tick bites. I use a Ti-Goat bivy but I may switch to some kind of bug shelter under my tarp this fall.

Best solution in this area is a good tarp and a bug net with floor hanging under it. It's generally too hot aroung this region for a full tent, IMO.