So i took the plunge and decided to go ahead with the Thunderbolt SSD boot. Getting around 200Mbp's write and around 360Mb's read. The difference is like night and day though, 15 seconds for a full boot. Just a couple of pics to show you what it looks like. Would definately recommend doing it if you want the iMac to be a bit "nippier" Excluding the SSD is already had it, the setup cost me around £150 which is a lot cheaper than the £480 for one fitted from standard. Happy to answer any questions. Will post a video of opening apps shortly.