I have the same machine for nine weeks now except I got the 256GB SSD. I also came from a Dell XPS 600(Pentium 4 extreme processor at 3.8GhZ) and XP Pro.
I turned off Intel RST permanently. It's junk. It will eat huge amounts of your RAM and your computer will become very slow. It eats a lot more RAM than any other process including Firefox with 150 tabs open. I have 16GB RAM but I knew something was slowing the computer, I opened Task Manager to see an Intel RST process eating more RAM than Firefox and way more RAM than any other process.
I'm kicking myself for not having researched this better before buying because I don't use RAID and I don't want my computer running in RAID mode when I have one SSD, with the OS/MyDocuments/Programs on it, and another WAY TOO LARGE rotational hard drive for storage (Dell did not offer a reasonable sized drive only the ridiculously gigantic one). I don't think the SSD (either size Dell offers is worth the amount of money considering all the headaches these drives bring).
I do not want to use Secure Boot either. I had it permanently off until I had a similar problem with the computer (like the first boot problem you described although a little different because it did not happen on the second boot as many who have the caching SSD have reported here, but happened after I had the computer over a month) hanging at boot on the Dell logo. I was read the riot act by Dell Premium support tech who told me that it was forbidden to enter the BIOS unless directed to do so by Dell hardware support (how ridiculous - besides Dell did not ask me to sign a document stating I would never enter the BIOS- I was expected by Dell to enter BIOS and expected to tinker with my XPS 600 so why would I think I was forbidden to do such things with this latest XPS machine) and told me that if I did not keep Secure Boot on that the computer would again, at random, lock up on Dell logo at boot and that the next time it might not be possible to recover.
The tech had me do what you described to fix the issue and then I said I planned to turn off Secure Boot again permanently. The tech said I could not do this as that would void my Dell three year Premium hardware warranty. That sounds absurd and, in my mind, Dell has done a "bait and switch" because they told Ed Bott of CNet in 2011 that Secure Boot would be set up where the user could turn it off permanently so that the user could dual boot with Linux, etc. But according to hardware support this is not true and Secure Boot has to be used unless the user reinstalls the OS in legacy mode or downgrades to Win 7 Pro.
This is what Intel says about using RST on a system without a RAID setup:
"Intel Rapid Storage Technology provides benefits to users of single drives as well. Through AHCI, storage performance is improved with Native Command Queuing (NCQ). AHCI also delivers longer battery life with Link Power Management (LPM), which can reduce the power consumption of the chipset and Serial ATA (SATA) hard drive".
I don't understand why I was told I must use RAID mode when I don't have a RAID array. As for Secure Boot, I will be turning it off again and if I have problems Dell will have to answer to their "bait and switch" tactic because I would never have purchased a Dell machine with Win 8 where I could not turn off Secure Boot permanently. Dell stated publicly that this would be possible on all Dells with Windows 8 but evidently that is not true. I want to dual boot and to do that Secure boot has to be off permanently.
I have zero interest in storage management using Intel's Rapid Storage Technology. Since you like it, I think you could just disable RST in Services until some solution is found.