if you seam seal properly or have someone who knows how to seam seal properly you will not get rain in...also there are products you can spray on your tent fly or roof to repel rain. your shelter should never weigh more than 5 pounds if youre traveling on foot. really it comes down to what the general weather is like in your area. i can hike in hawaii and just have a bug net and a tarp. if im going to go to nepal id want a hilleberg, if i was in patagonia id want some SERIOUS silicone impregnated material with awesome seam sealing.

again i must say sixmoondesigns is the tent i would go with the Lunar Series is AWESOME and the Refuge is nice as well. i believe they offer seam sealing for like $20-$30

also the ultralight series from seirra designs isnt bad either.

but if your worried about rain then seam seal your fly or tent canopy. if its really raining buckets you might want to carry a lightweight tarp to pitch above your tent at a slope. if you do seam seal make sure you get the right sealant for your material.