I posted a question similar last week as I was looking at a 27" with either i7 and/or SSD and if SSD was really worth it. My use was running multiple VM's. One member sent me a PM giving me the following advice.
First choice - If you can swing it, get both (i7 and SSD). Even though the apple SSD's are slower than 3rd party, they're still faster than the standard drive in the machine.
2nd Choice - Go i7 and possibly upgrade to the SSD drive later. When it comes down to number crunching and flat out raw horsepower, the i7 spanks the i5 hands down. That will help with the overall processing time and having hyper-threading on the i7 doesn't hurt at all. When it's time to upgrade to the SD, get a 3rd party one and install it (yourself or an authorized service person). OR... Save up for a bootable Thunderbolt device (Promise Pegasus R4 for $999). There are devices that are starting to pop up with SSD's in the thunderbolt device and are bootable. You can then configure the internal drive as a scratch drive, backup bootable drive, data drive, etc. Thunderbolt has a lot of potential. Plus if you get a bootable one, when you upgrade the machine in the future you should just be able to plug it into the new machine and off you go. Thunderbolt is pricey right now but it should start coming down as more products come out.
3rd Choice - i5 with a SSD. It will appear and feel faster, but under heavy processor intensive tasks it will still struggle.
Once I started thinking about it again, I think I would opt for the 2nd choice.
Also, I know many people with refurbs and they have 0 (ZERO) issues with them. Majority of Refurbs are customer returns and not because of a hardware issue. Customer changed their minds, wanted something different, etc. All refurbs go through testing to make sure they are as good if not better as a new product. If there is something wrong, the part is fixed/replaced. Just like if you bought one off the store shelf and had to get the motherboard replaced at the store 6 months later. They carry the same warranty as a new Mac and you can get Applecare to extend the warranty to 3 years. Really for me, there is no reason for not getting a refurb unless you just have to have new. And sometimes they'll get a "free upgrade" like 8GB of RAM, etc. Speaking of RAM, max out your RAM when you get it. You can get 16GB kits for under $150, no brainer especially for what you're doing. Or you can drop 32GB of RAM into it for $1400...
Hope this helps. I now know which way I'm leaning once the boss approves!!