Just ordered one for myself for a hunt and another trip..I wanted warmth as the other trip it will be extremely cold.
I was curious as to how much of a difference an RF value of 2.5 vs 5 would realistically be?

You might take a look at the Big Agnes insulated air mattress. It is light weight, is very comfortable, and packs down to a small size. The down side is that it is an air mattress...it can leak if punctured. If you use a ground cloth, bivy sack, in a tent you are fine. I have one that I have used for 3 yrs now and am sold on it.
I also have had for many years the ThermaRest that work good too.

Stick with the plain old thermarest foam pad, air mattresses are great until they get a hole, then you have 2 thin layers of plastic between you and the cold ground! This can totally affect your sleep, and when hunting the backcountry, sleep is a top commodity!

If you don't mind the little extra weight (+7oz), and the cost, an Exped Downmat is hard to beat. The tiny repair kit that comes with it is idiot proof, and the comfort is great, especially in cold weather.

It is a piece of gear that if you spend a lot of time outdoors is worth it, but for five nights/once a year a little tough to swallow for most.

I used the Thermarests for years.Before that a 1/2" Ensolite pad.I use the Big Agnes now and really like it.It is about 2 1/2" thick,very comfortable and well insulated.Come up with a list of ones to consider,check features and "R" values then search for reviews.REI should have some as well as an article on how to select one for your needs.

When backpack hunting I use a ThermaRest over a common US GI foam sleeping pad.

I have yet to be cold even in the snow and rain at elevations of 9,000 ft+.

I also use a USMC cold weather sleeping bag made by Wiggy's and a Gore Tex bivy sack.

Hope this helps.

Charles.

QuoteOriginally posted by DXH:
I was curious as to how much of a difference an RF value of 2.5 vs 5 would realistically be?

It will be significant. For cold nights, bring a cheap closed cell foam pad and use it on top of your uninsulated Thermarest. An uninsulated Thermarest sucks the heat out of you in the winter, but the foam pad makes a big difference.
The foam pad is bulky, but light, and if you are really weight conscious, cut it to 3/4 length.

the Thermarest Camprest, it's a little thicker and the air pocket definitely helps keep the cold at bay.  If you're going to really cold area don't try and assist the inflate, the condensation from your breath will freeze up inside and that starts a whole new problem.

Big Agnes air mat for me.  I carry a repair kit.  Its the only thing not worth skimping on weight in my book.  A good night's sleep means everything and those tiny foam mats on the ground just don't work well for this side sleeper.

I've had a Big Agnes Insulated Air Core pad since they have come out.  I have not had any issues from Arizona to Alaska with it and it is more comfortable than sleeping on my bed at home.

I use both a thermarest and a 3/4 length piece of the green military closed cell pads.  I always carry the military pad around, even when I don't have my tent with me.  It's great for spotting.  Rocks get cold and hard quickly.

2.5 vs 5 basically means one is twice as good as the other.  

How much pad you need is inversely related to how old you are.

Mostly use a thermarest camp rest for fly out and boat trips.  Use a cheap ensolite pad for packing aways, and as was said above, its great for sitting on too when you're glassing for a long time.  If I'm going really light a lot of times I won't take a pad, heck I roll off the pad half the time anyways.  But I definitely use a pad in the winter, or when there's snow.  And don't forget about spruce boughs.

I have the Big Agnes Air core as well. I put a piece of tyvek house wrap under it to help protect it, as well as a barrier between it and the ground. The Tyvek doest weight really anything.

If you can afford the weight and bulk then two pads combined are more comfy an a lot warmer in all conditions and you have a spare as mentioned.

I also use and love the Big Agnes insulated air core.  Awesome pad!

X2 on the Exped

QuoteOriginally posted by LKH:
How much pad you need is inversely related to how old you are.

You ain't kidding!!  I still use a therma rest 3/4 backpack pad all over the country and in sub zero temps in a bivie sack.  I know it will catch up with me someday.  dino

Go to a military surplus site and get what us Marines slept on olive drab foam mat that is really good, tough,light and keeps the cold off your back.And it wont cost an arm and a leg.

I got a therma rest NEOAIR as a present last year.  It is amazing.  If you like ultralight, its the cats meow.  Its not cheap, but I would recommend it strongly.  It condenses to the size of a nalgene and weighs less than a pound.  It is made of a reflective material like survival blankets,inflates, and is very warm in mountains.  I like to save the pack weight and space in my llama train for food in the summer and meat in fall.  

montana- how durable is it? im gonna have to check that out