SSD speeds

I'm researching some info on the capabilities of certain computer builds. My SSD using SATA 3 SSD connection to my mobo specs gets around 540mbps sequential read and around 520mbps sequential write. The spec allows for "up to 600mbps".SATA express allows for around 1967mbps.
 
In researching this I noted that the Samsung M.2 500 gb card SSD that uses PCIe lanes specs the same as my Samsung EVO 500 but has less anticipated lifespan. I see no real advantage to using the M.2 SSD.
 
I'm wondering if anyone is using any of the SATA 3.2 or SATA express drives? Do you see any advantages?
 
SATA express seems to be long term interim solution since it isn't widely used and doesn't seem to be catching up with the capability of some SSDs.
 
 SATA express has an impressive speed . It seems though that none of the setups I'm seeing are really taking advantage of that capability other than video card manufacturers.
 
There has been some mention of using a dual RAID on SATA express to get blistering speeds. 

I think I'm partially confused at the terminology since M.2 slots can support both SATA 3 and PCIe. The comparison I made was to a standard SATA 3 M.2 drive I think. These drives have the same or similar performance  as SATA 3 SSD . Around 600mbps.
 
What you're calling "ulta" must be the M.2x4 standard. I wasn't as familiar with that standard.
 
These drives need 4 PCIe lanes to get the job done right? And this is where a it can slow down additional hardware on some motherboards and cpu configurations. Taking the extra bandwidth to run these drives can potentially hurt performance on another slot.
 
I can't imagine booting off a drive that reads at 2000MBPS :)...The median lifespan of the M.2  was shorter. My Samsung SSD EVO 850 was rated at 2000000 hours. The M.2 version was rated for 1500,000. 

Thanks guys. Good point Dan! I hadn't thought about that. Data only written once and only accessed isn't working those NAND gates as much. I was going by the specs for a Samsung 850 EVO and the specs for a Samsung  SM951.M.2 socket 
Look at the hours under "MTBF" under specs. for each drive.
 
http://www.newegg.com/Product/Product.aspx?Item=9SIA12K3GB5852
 
http://www.newegg.com/Product/Product.aspx?Item=N82E16820147441&cm_re=samsung_evo-_-20-147-441-_-Product
 
Why is the SM951 rated for 500,000 less hours use or Mean Time Between failures? I understand that the number is "estimated"...still there's only about 8700 hours in a year. 
 
Here's some info on MTBF...I'll need to research it more, because I don't think that number is in hours. If it is wow.
https://en.wikipedia.org/wiki/Mean_time_between_failures
 
 
 
 
 
 

I think it was a great observation Dan. I also think maybe it has something to do with the lifespan of the card and socket form factor. I really don't know. 
 
I can certainly see the reason to go from SATA 3 to M.2x4. Standard M.2....not so much. The only real benefit I'm seeing is it's probably less expensive to make since they don't need a shell for it. 
I think the sockets should click into a solid connection the same way memory cards do. A simple plug in type of thing looks and feels flimsy from a mechanical perspective. With 12 sata ports on my mobo( and I'm not an exception) I don't see the need to free up real estate on my SATA connections. If I took two ports for DVD/CD. I still have room for 10 hard drives. I don't know about you, but unless I had some kind of a hard drive fetish, I doubt I would ever think about that many drives....well ok, if someone had some cool drives they wanted to give me maybe :)
 
My first link above in the comparison was supposed to compare an typical M.2 drive ay the same read speeds.. I accidentally used a link for the faster M.2 x4 link. The life span  seems to be rated the same though.

Starise
 
The median lifespan of the M.2  was shorter. My Samsung SSD EVO 850 was rated at 2000000 hours. The M.2 version was rated for 1500,000. 

I saw this statistic fly by but not sure where this spec came from (or that it is truly hours?). 2,000,000 hours = 228 years... "only 1,500,000" is still 171 years... I do not believe either one, unless the SSD was hermetically sealed and kept in environmental storage for that long.