Upgrade to Yosemite question

I'm planning on upgrading to Yosemite from Mavericks on a Mid-2010 MBP 15" with a Samsung 840 PRO drive as the primary drive. I have TRIM disabled! The process I want to use is as follows so I'm just looking for a validation please!

1. 
   

   Make sure Time Machine backup is current and good. I'll restore a single file to verify.

   
   


2. 
   

   Verify TRIM disabled via System Report. Shows "TRIM Support: No"

   
   


3. 
   

   Download installer from App Store and run upgrade in place.

   
   


4. 
   

   Once done, reboot.

   
   

If all is well:

1. 
   

   disable signed kernel extensions.

   
   


2. 
   

   Install TRIM Enabler

   
   


3. 
   

   Reboot

   
   

Should be done.

Are there any problems with this methodology that I should be aware of?

Is there a significant advantage to a clean install versus upgrade in place? I know there is for Windows, but I've upgraded this system twice now with no problems.

Thanks in advance for the advice.