speed is identical. 2.5 sata is slightly cheaper.  a 128 gb new 2.5 sata can be as cheap as 20. a new mstata 128 gb can be as cheap as 26.  price is pretax on eBay.  used price is everywhere. durability?  it depends on brand and technology used in making the ssd.  If same brand (for example Samsung and same NAND tech), then it is the same.  the 2.5 vs mSATA is just form factor difference.  both access same sata controller and read/write the same way.  mSATA has smaller foot print and no messy cable of 2.5 sata.  on the other hand 2.5 sata is easier to swap in and out and some people have a stash of them in their bins.  not many have a stash of mSATA which is used in older desktop and laptop. Re: It seems that mSATA needs to have special size screws?  no just small metric screw.  The mSATA SSD requires two M2 screws. Re: brand name brand only.  no never heard of name or weird name.  I will go with what Dell OEM uses such as LiteOn, Samsung, Toshiba etc.
After checking the previous thread, my understanding is that there are two options for XPS8700 to upgrade its storage with SSD: either mSATA SATA SSD. ( please let me know if there is another way to do it) I want to hear suggestions on which type of SSD is better, regarding durability, transfer speed, and cost? Any specific suggestions on which brand? It seems that mSATA needs to have special size screws?
XPS 8700, which SSD is better, mSATA or SATA SSD?