looks like a machine, that yes is not a desktop, but regardless should be able to handle whatever is thrown at it for 4-5 years.
http://www.notebookcheck.net/In-Review-Nvidia-GeForce-GTX-780M-GTX-770M-GTX-765M.93277.0.html
as it stands the gtx780m is capable of completely maxing out some games at 1080p however even some current gen games like crysis 3 and similar high graphics games can absolutely crush the mobile card to unplayable fps unless you lower the quality. typically you would reduce the AA to try and make up for it.
if you follow the history of gaming graphic improvments as well has how it affects hardware the newest games to come out will likely make crysis 3 look less like a beast and more like a kitten. if you have a machine that could max out crysis 3 now it would likely be crushed as well for the new generation of high end games let alone an underpowered mobile gpu. truth.
i will be entirely realistic here: that laptop will likely be able to have 1-2 years of good gaming peformance followed by some average gaming performance. it will max out all older games as well as a few newer titles depending on the graphical requirements however for crysis 4, battlefield 5 or whatever new games come out which can be demanding on graphics you will have to cut back on the graphic settings to make them playable.
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what i found on msata vs sata is that it is essentialy meant for laptops as a way to shrink everything down.
i did find this interesting quote though
mSATA drives are almost always 4-channel which is slower than their 8-channel 2.5" counterparts. Your sequential reads and writes don't show a lot of difference but when you get data on the flash the mSATA parts slow down faster. Random performance takes a larger hit as well with 4-channel parts but again, when data is on the flash.
as well as a claim from one of the gpu manufacturers stating that the ports were very similar and that there wasnt any performance increase.
cant verify this by testing since i dont have two to compare but from what i've read around you can expect anywhere from around the same performance to a slight hit in performance. it will NOT be a performance gain though.
i do believe this answered both your questions which essential was "sata vs msata" and "is the gtx780m good vs ..." since you can read the performance charts i listed above and compare for yourself. drivers do have a bit to do with it as well and often its a crapshoot between nv and ati depending on specific game drivers. unless of course some revolutionary product comes out which isnt the case right now.
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since you seem set on raid arraying ssd drives... go ahead and do it. just realize that you arent going to notice the difference especially for your application (gaming) and that you wasted about $700 more than you needed to.
my laptop is a few years old now and was only a mid ranged laptop with a 635m and without a 1080p screen however i used it for casual gaming. i ended up putting a samsung 830 256 into it and the boot time and windows snappyness are great. gaming performance however is not affected.
if you want a gaming laptop your best bet is again... a boot ssd and a normal hdd drive.
the 840pro 512 is also a good choice. remember there is a definite diference between the "pro" and the "normal" version which mainly is the type of flash used. the pro will last longer and is more reliable although samsung in general (as well as intel) are far above the industry norm in terms of reliability of ssd drives. most other manufacturers fall way short.