I would suggest you make a list of what things are important to you in a shelter and the conditions you will encounter. Their is no perfect shelter for everyone. Could of things;
- Are you looking at a 2 person for the extra room or because you will share the shelter
- If you are sharing the shelter I would select the REI T2 (I just made that decision for a shelter I will share with my brother in law). It has two doors, vestibules for gear and is pretty light. Would not take it for just me however
- I like side entrance because it is easy for me to get in and out than a end entry. I also have the option to do some cooking in a light rain (depends on the shelter)
- If you get much rain how to do feel about dealing with it. I have road out some pretty heavy storms with high winds and heavy rain under my Trailstar without any issue. Only issue is getting in and out of the shelter on the soggy ground. Not a big issue for some, but those that need to get up a few times during the night that can be a pain
- How are the bugs in your area. If you pick a Trailstar, Tarp, Duomid, etc you will need to deal with a bug bivy or inner net. I have both and they are a real pain to me. However many love them and have no issues.
- In cold weather and wind things like bivy, natural wind blocks, site selection become more important.
- In the late fall, winter and early spring you have a lot of time in the shelter. Are you a guy who can sleep for 12 hours or do you like to chill in the shelter for awhile (journal, cards, read, etc). You might like a little more room if you do these. If you go to bed and sleep 12 straight hours then you have a lot of options.
I would suggest thinking through conditions. You don't pick a shelter based on good weather/conditions. They all work in those cases. Couple things;
- you just hiked a long day, its now raining and getting cold fast. You need to setup shelter, cook food, hang bear bag, etc.
- first setup shelter on wet ground. If you shelter doesn't have a floor, then you need to put down you ground sheet
- now it's rainy, ground is wet and you are under the shelter on groundsheet. Now you have to get bed ready, put on sleep clothes
- You ok doing this in a floor less or would you prefer being in a floored shelter doing this.
- It's time to get up and start hiking. It's rainy. Now you have to pack up your backpack and hit the trail.
In my opinion, single or double wall is not the question because I think either will work. To me extra pound of weight doesn't really make a difference and doesn't effect my performance. It all comes down to what works for you and fits your style. Now you have to pick where you spend the extra weight and don't fall into the trap of just carrying extra weight.
For the record I have several shelters and pick based on the forecast and my mood.
MLD Grace Duo
MSR Carbon Reflex 1
Just my two cents and many others here have more experience.