2011 iMAC SSD upgrade options

I have a mid 2011 27" iMac with a conventional HDD.  It's time for an upgrade looking to boost overall performance.  I have a another 7 year old iMac I just upgraded to an SSD and in some respects it is faster than my newer 27".

I would like to upgrade the system drive to an SSD.  User data will be kept separately (External Raid 5; likely promise R4).

I am considering two main options:

(1) Internal SSD - would have someone replace both the main HDD with an SSD and also add a similar SSD to the internal SSD bay.  I would then run the pair as a Raid 0 stripe for maximum performance (both on SATAIII).  This option is likely the least expensive, and gives the greatest performance.  However, the machine still has 1 year of AppleCare left and I am concerned about support and possible problems messing with the machine guts.

(2)External thunderbolt SSD; likely Raid 0.  Go with some form of external TB SSD.  Least expensive option would be a simple Lacie Rugged SSD 120Gb.  These are under $200.  Not Raid 0, but still a likely big upgrade in performance over the current internal mechanical HDD.  Top end of this range would be an OWC Helios 120Gb.  Advantages here is that drive is likely itself upgradable as larger SSDs arrive plus if there is ever a problem, I can just unplug the drive system and run off the stock internal HDD.  Alternatively, I can simply move the drive subsystem(s) over to a new machine.  Other options include the OWC LaCie TB--eSata adapter and some Estat enclosures with SSD; also a Promise R6 with two of the bays as an SSD Raid 0; the other 4 bays as HDD/Raid 5 for data (keeps entire disk subsystem in one box).

Anyone go through this thought process?

Thoughts?

db