I personally prefer a full-length zipper because it's easier to ventilate on warm nights. Otherwise, judging from the specs, this sleeping bag sounds very similar to the discontinued REI Sub-Kilo (which REI seems to have finally sold a considerable inventory). I suspect the Pertex shell on the EMS bag is probably superior to the polyester shell of the REI bag. I notice that they don't give the loft measurement or mention an EN13537 rating. In view of that, I would consider this a 25* F bag rather than 20*F, which of course you can take down another 5 or so degrees by wearing said insulating clothing inside. It does sound like a good buy!

Pay particular attention to your girth measurements (shoulder 60", hip 54")--to find out yours, measure chest around your arms and shoulders wearing a puffy jacket and hips also over insulating garments. If the girth is too tight for you, you'll compress the insulation and the bag won't be as warm. If the girth is way too big, you'll have extra dead air space to warm up on cold nights. Even more depends on whether you want more or less elbow room! If you mail order, be sure to try the bag at home (wear your insulating clothing) as soon as you get it to be sure the width is correct for you. If you can visit the store, again take your insulating clothing with you and try on the sleeping bag.

Another fitting tip--if you are right on the cusp between regular and long, get the long.