I have a ID MK1 XL. Great tent for altitude, cold weather situations. Silnylon vestibule is available. Trail weight w/o stakes and guy lines is 4 lb 2 oz, with light floor. Silnylon vestibule adds another 14 oz..
This is a Toddtex tent (basically Goretex w/o polyurethane coating on the PTFE membrane so its highly breathable). Breathable and robust. It is free standing, quick to set up, able to withstand high altitude conditions. With the vestible you can cook in bad weather, or if you are in rainy, humid areas, it allows you to keep the front door open for ventilation. The vestibule is almost essential in windy/rainy conditions with the alcohol stove. On a sea to summit trip to 13,600 feet Maunaloa, the MK worked great, the vestibule allowed me to cook in windy conditions with out a problem. I was using an alcohol cat can stove which is wind sensitive (even with wind screen). The single wall tents also add warmth which is a big plus for anything involving cold, winter or altitude conditions. Set up of this tent is a breeze and being free standing allows for pitching on a small foot print.
If you need a light, completely waterproof, all conditions tent, this is a good choice. Beware of Epic as it is only water resistant while the Toddtex is completely waterproof.
It depends on how much comfort you have with Epic, but for worst case scenario, I'd go with something that is classified waterproof.
While total trail weight with silnylon vestibule is at 5 lbs, this tent is fast to set up and bombproof. Great design, made in Canada. ID is a great company, excellent customer support.
As far as bombproof or not, depends on where you are going. If you are going in altitude or winter camping, you don't want to go too undergeared on the tent. Bad weather can kill so look at that too. But if you are not going to be doing altitude or winter camping, you could go lighter by 2 lbs with tarp tents or ultralight 3 season tents, e.g. Big Agnes Seedhouse 2 ultralight freestanding tent. Definitely get the tents and take a look at them, if you don't feel comfortable with them return them, worst case is cost of postage to and from, but you want to have something you feel comfortable with.
Tent and backpack are 2 things that you may not want to go super light on since they are critical core items that you don't want failing. See Dan McHale's website on packs, http://www.mchalepacks.com. Dan's letter is interesting and the packs while pricey are top notch. He's doing them now in spectra which is super light and super strong.
The tendency with the ultralight movement is to push the envelope on the gear weight, but also plan on worst case scenario because if you are undergeared, it could be bad. Can't control the weather so be prepared.