I've got both mate, the 2 and the 3. For the price I'd say they're great. For backpacking alone obviously the 2 would be better but the 3 would be fine if splitting the load with someone else. There's a pic of the 3 on Amazon beside a helmet with gives an indication of pack size. The 2 is a fair bit smaller when packed. I don't know the weights off hand but you probably know them.
So far I've found them both to be pretty waterproof. They're rated as 3000mm hydrostatic head. Once in a few days of torrential rain the water was coming through the outer fabric but it just runs down the inside without penetrating the inner or groundsheet.
I replaced my 2 with the 3 for a few reasons. I take it on my bike so size and weight don't matter. The 3 has more room for bike leathers, helmet etc in winter, and the 3 has more room to sit upright. The 2 is a bit low for me with my bad back (I'm 5'6''). Having winter bike gear is like having an extra person in there so the 3 is better for me in winter.
I use alight cheapo tarp underneath the groundsheet to protect it and that helps with waterproofing as well. The groundsheet can absorb a lot of damp if placed bare on wet ground. Although I've never got wet in mine they can become a very damp environment if wet kit is brought into the tent, or if the groundsheet is laid unprotected on wet ground. I don't know if all tents are like that or if a 5000mm rated tent would be better. I believe all tents by Vango are 5000mm. As I say I haven't got wet though and I'm outdoors a lot in winter. I like the cold. I've slept in the 3 at between -5 and -10 last winter.
Despite what some reviews say on Amazon they both go up outer first. The 2 is pretty small for 2 people. The 3 will take two plus a fair bit of kit, and for one plus winter gear plus winter bike gear the 3 is ace.
Hope that helps.
