4x SSD in RAID or 1x M.2 SSD?

[Kapellomg]

So I was just looking around for storage, considering options for my next PC build. I noticed that I could get a SATA SSD with read speeds of 133.120IOPS for just 40 euros, now if I were to put 4 of these in RAID 0 or 5 of 'em in RAID 1 (redundant thing) it'd only cost me 160/200 euros, if i were to get an M.2 SSD with a rating of 330.000IOPS it'd set me back 250 euros, only thing I really care about is 4k random speeds. (IOPS) should I go with a RAID config then or is the M.2 worth paying a premium for?
oh btw, the SATA SSD is 120 GB's each (480 total) and the M.2 is 512GB

 

[bootcher]

The 'real life' performance depends on your hardware, specifically the raid controller. In theory it could perform above the m.2 SSD, but in real life it might not. In my experience SSD's in raid usually don't hold up to the promise, they can actually perform worse than a single SSD, this is most likely the case when adding up more disks to an array, as you would do with an array of 4 disks.
You should do a bit more research on how your motherboard/chipset performs in raid arrays.

 

[geofelt]

Raid-0 has been over hyped as a performance enhancer.
Sequential benchmarks do look wonderful, but the real world does not seem to deliver the indicated performance benefits for most
desktop users. The reason is, that sequential benchmarks are coded for maximum overlapped I/O rates.
It depends on reading a stripe of data simultaneously from each raid-0 member, and that is rarely what we do.
The OS does mostly small random reads and writes, so raid-0 is of little use there.
There are some apps that will benefit. They are characterized by reading large files in a sequential overlapped manner.

Here is a study using ssd devices in raid-0.
http://www.tomshardware.com/reviews/ssd-raid-benchmark,3485.html
Spoiler... no benefit at all.

I found there to be little benefit of a 500gb Samsung 950 PRO m.2 stick vs. the previous 500gb Samsung 850 PRO.
Yes, it was faster in virus scans, but that was about it.
I do not much like the requirement to mount it on the motherboard under the graphics card.
Really, not much worth it.

If you want a real boost in performance look to the upcoming Xpoint Optane devices.
In the mean time a standard 2.5" format does the job. Samsung today seems to be the best.