Erase HDD vs. just erasing the files I don't need. What is more stable?

[digitalninja]

I recently installed a 256GB SSD into my MacBook Pro. The original HDD was cloned, so essentially right now I have 2 copies of my System Drive in my Mac. Now that everything has been tested I would like to streamline my setup.

I want to use the original HDD for my sample library and Logic and Ableton's loops and sounds.

I would like to erase repeated data on my HDD or reformat it. Since the apple loops and samples are all in place on the HDD would it be better to just erase the things that I DONT need any more (the majority of the Library and Applications being the biggest culprits) from the HDD? Or should I just reformat/erase the HDD and then move what I need from the SSD?I've read the process for moving the content, I'm just wondering if one of the methods I've described is better for overall system stability.

My ultimate goal is to get rid of the extra external sample drive I've been taking with me when I travel.
I tried posting about it before here (with no response) http://www.logicprohelp.com/forum/viewtopic.php?f=1&t=88752&p=465348#p465348

but I'm really trying to get some expert advice before I make a big mess. I know my Mac/Logic's a bit touchy about some things.
• Logic 9.1.3 • MacBook Pro OS X 10.6.7• 2.66 GHz Intel i7 • 8GB RAM • 256SSD, 500GB 7200 SATA & Lacie Rugged 1TB

 

[kave]

Deleting an operating system and all of it's files from a hard drive is not recommended. Further it will have fragmentation that slows down performance.

A format is much quicker and better in your case.

 

[yjchua95]

Back up whatever you want first (I recommend SuperDuper!)

Do you have the restore dmg for your OS?
If no, better make a bootable restore disk (here's the complete way: http://arstechnica.com/apple/2012/07/how-to-create-a-bootable-backup-mountain-lion-install-disk/
However, I recommend the DIY way which gives me more control).
After that, just boot from the bootable USB, reformat your SSD with Disk Utility, install the OS like usual, and there you go!

It's better to reformat because you don't know how much junk's piled up in the not-so-accessible parts of the hard drive anyway. I personally do that myself. And with SSD + Thunderbolt drive, backing up doesn't take long.

Cheers mate!