Well in my case I am mainly looking for a lighter suit to travel with, etc. If the emotion suit would have been available and I had seen it in person, I would have bought it on the spot, it just looks sharper, and feels better when wearing it IMO. There is more to it which I will elaborate belo:
Durability:
The espace is basically comparable to the CLX450 from DUI, the suit is a tank, not literally but it is highly abrasion/puncture resistant, which is good news. The material weight is 420g/unit measure(can;t remember if it is metres or feet)/ The emotion material weight is only 260g but it is of a ripstop material. IT is not as abrasion resistant as the espace, however what santi has done, is used a lighter weight material for the construction of the suit, and added in what appears to be the elite material(460g) in the areas of the suit that see the most wear (seat, knees, butt, forearms/elbows) What this has done is created a light suit that is extremely durable in the areas of high wear/punctures. etc.
Fit
The espace is cut a slight bit larger from my research to account for the material, it is flexible but from my understanding it is not nearly as much as the emotion. The stock emotion I tried on in my local shop, I could stretch the material a fair bit more then the espace. Typically this allows for a much better cut to the suit in my experience, although I may be wrong on this.
Features:
The espace suit as weith all Santi suits, come with pockets. They do the job, however I prefer the elite pockets and had those installed instead of the espace ones. There are no knee pads on the espace and I had those added as well. At the time the t-zip was not an option, but since i am due for a new zipper here very shortly this will be added onto the suit. The emotion come with all these featured right out of the box, so it is just less to add onto the suit as it comes with them stock.
Price:
The stock espace has the emotion beat in terms of cost. That is until you start adding features, like knee pads, better pockets, etc it quickly will become more if not equal to the cost of the emotion (~5-600 dollars for pockets and knee pads, might be less now).
Accessories:
This is on a side note, but if you are getting accessories added to the suit, get the sitec neck ring, however avoid the antares wrist change system (they are just junk) they do no always pop off, go with a diving concept/kubi style dry glove ring system, much better and you will not go wrong. Seal changes take literally an hour and you can sit back and enjoy a beer. That and wrist seals do not see the abuse the neck seals do and tend to last longer and if they do fail you have the ring system installed so you can continue to dive with dry gloves, just glue new ones on when you get home. Neck seals are different, they tend to catch on things when you havee the suit half on, etc so I have a quick change system there, so I will not loose a dive if that happens. If you are getting a p-valve installed on the suit avoid Light Monkeys, they are notorious for not working properly, sure there are people who have them and they work fine, but do some digging on other boards and others will agree, there is sometimes materials left in the valve the obstruct the valve from working. I would suggest halcyons, they seem to make the best and I have never heard of an issue, except for one that had the duckbill portion go, easy fix. Just my two cents and from many years of diving drysuits and on the hunt for good gear.
Can you talk a little bit more about why you're switching from the Espace to the E.motion? I've been reading about both of these suits (and the E.Lite) online. Other than being about 25% lighter, it's not clear to me what the other differences are. Of course, Santi's marketing materials make all the suits sound ideal (and I'm sure they're all awesome in their own ways), but they leave me failing to understand why I might choose one model of suit over another.