Not really the hardware is different so what you would need to do is install all your drives and perform a server recovery and even that's different with the EX49x vs the EX48x. Because the recovery is different I would recommend you do a test run using a singe drive performing a factory recovery. This will give you an idea of how the recovery works and with a used system its always a good exercise to do just to make sure its working properly. After you get the hang of it then you can do a Server Recovery with you existing drives or you may just want to play move the data between the servers and use BDBB to backup your current client backups off the EX48x and restore them to the EX49x.
Because the recovery method is very different with the EX49x you may want to review the information on recoveries from the sites WIKI:
http://www.mediasmartserver.net/wiki/in ... _and_EX495Here is a Guide on how to migrate from and EX470 to the EX495 which you may find useful and can apply to your EX485 migration to the EX495:
http://www.mediasmartserver.net/2010/01 ... me-server/This is a guide on how to use a Server Recovery to move your data between two WHS Servers. While the servers are different the same basic idea applies to all WHS Servers:
http://www.mediasmartserver.net/2009/09 ... me-server/Another Guide using a Server Recovery with two HP MSS Units:
http://www.mediasmartserver.net/2009/08 ... -hardware/Personally if it were me, my #1 goal would be to protect my DATA at all costs which means I would be taking the more expensive route setting up the EX495 first to make sure it was working well and I would install all the HP & MS Updates and of course add in a new set of hard drives to hold my data. I would use BDBB to backup my client data off the EX485 then restore it to the EX495 and then install the client software on all my clients so that the EX495 would be backing up the clients from this point forward. Then I would copy my data over to the new server and leave the EX485 alone for a period of time until I was fully confident the EX495 were running well.
I know its more expensive but it reduces the risk of losing your data and still allows you a way to still access the data while your migration is taking place. Should anything happen to the EX495 along the way you would still have a fully functional server to fall back one. This is how I migrated form an EX470 running with like 8 Hard Drives over to an HP ProLiant and then later when I built my WHS2011 server I did the same thing again and my server size was much larger then a 4 drive unit in both cases. With each migration I kept the data safe on the previous server and later I reduced the previous server size down and moved the hard drives keeping only the most important data on the previous server for additional redundancy.
However if you have a large server system like I currently have this may not be as practicable and so the Server Recovery method maybe you best option to save funds on new hard drives. Its just the means in which I have done my migrations in the past but today if I were to do the same thing it would be extremely expensive with my drive compliment.
Today I still have my last work horse WHSv1 server running and its still preserving my important data and doing other tasks for me and that WHS2011 server is now running WS2012E but for that migration it was a much easier process because of the way Stablebit Drive Pool allows you to migrate your entire storage pool from one device to another but that's a totally different subject matter but none the less its all about protecting your data and in your case about getting us to how a recovery works on an EX495 which I find to be a bit troubling but when done right it works quite well but often it could take a couple tries to get it working.
Good Luck with your migration. I think I have provided you with all the information you need to help you to determine which migration method will work best for you but I do encourage you to weigh in all your options.