Pertex Endurance

I don't really see a comparison here, Endurance is a shell fabric and used largely on highend sleeping bags. I have a custom ID winter bag with it and it is absolutely superb in wet conditions.

I have two ID eVent shells, two ID eVent bivies and may buy an eVent ID shelter, when it is finally on the market. This seems a heavier fabric, mine have performed VERY well and I am totally sold on it for garments and bivies. However, what I have seen is much too heavy and stiff for sleeping bag shells, it would be like using a huge, toothed plastic zipper where a fine coil zipper would do.

They just have separate uses, IME and O.

I would say it depends on where you'll be – temp and humidity. I have an Endurance overbag and it's totally waterproof and windproof, though a bit heavy and crinkly. eVENT is lighter weight (usually), waterproof, and breathes better. And is much more expensive. If I were buying a bivy I'd go with Endurance, but for a jacket eVENT can't be beat.

MLD uses a two layer event for some bivies which is much lighter then the "standard" three layer event. Care is required to prevent damage to the membrane but the inside face of a bivy is not a high wear area in most cases. If storing something, such as shoes, at the foot of the bivy in cold weather simply place inside a stuff sack prior to sliding these into the bivy, this will help protect the membrane.

Just to confuse the issue some more, there are 2 types of Endurance. Pertex Quantum Endurance, and Pertex Endurance. I'm not sure if Rab still use the Quantum Endurance.
I have a Rab Quantum Endurance 250 sleeping bag. It is about 5 years old, and is still very water resistant after hard usage. I've never had the down wet, and the bag has been used in some very wet conditions. It's never felt 'sweaty' either.
I also looked at the Ultra bivvy when it first came out. I e-mailed Rab for dimensions of the bag. It is a snug fit, and that stopped me buying it.
I can't remember the dimensions now.

LOL David!
I'm using a quilt now, so i like plenty room.
It's probably fine for a sleeping bag.
"All i did for you" was force me to spend money! :)

I just found an Exped eVent bivy with a FULL side zip and am going to buy one, without question. I want this for my frequently solo trips as I can more easily get into it if I fracture a leg. ID will NOT make me one and so Exped gets my bux.

My eVent fabrics are HEAVIER than my Endurance one, but, there are probably different types/weights of both. I agree on eVent for jackets, I am totally sold on these and plan on buying a couple more, probably from Wildthings.

Wildthings also makes a nice full event bivy.

David,
The event membrane is exposed on the interior of the bivy. MLD does not make a full eVent bivy but opts instead to use a non-event material for the bottom. The exterior surface of the eVent material is not an issue. If you visit the MLD site look at the pictures of the MLD alpine bivy, the white interior of the upper fabric is the eVent membrane that requires care.

I too am interested in the Rab Endurance overbag due to weight, price and the side zipper.

Have you seen the BPL review of IDs Endurance Bivy from 2002? The review states of the fabric:
"The fabric is almost waterproof. Pertex Endurance is a reasonably breathable fabric, breathing nearly as well as popular waterproof-breathable fabrics with laminates, membranes, or microporous coatings. However, do not expect the Endurance Bag Cover to remain condensation-free in wet, humid conditions."

I intend to get the Rab bivy for winter use in a floorless shelter provided it is large enough for my 0 degree down bag and a 3/4 length foam pad. It will not breathe as well as Event (nothing does in my experience) but for the weight and cost I can handle that minor issue.

The eVent bivy I mentioned is from Exped and is on the OR website. It seems to have the features that ID will not put into theirs and I want, so………

As to Endurance being waterproof, I camped high on a ridge in April, 2004, a year after having my custom ID-XPDII made with an Endurance shell. I was in my old NF VE tent and was hit by a severe storm for a couple days/nights.

This pos tent was SOAKING, just running with water inside and my bag got drenched….it never leaked a drop and was bonedry when I got home after four days/nights. I LIKE Endurance shells on bags, but, would never buy a bivy made from it; eVent is THE "bomb" for bivies and garments, IMHO.