Suck it and see. If you can live with having to remember to copy any results that you are fond of back to a physical disk then the ram disk will probably be even faster than an SSD (but not by all that much).
I haven't gone down that route myself.
Extra ram is cheaper than any SSD so you could easily take the total up to 16GB. I'd still recommend having an SSD like the Samsung 840 Pro for storing regularly used bulk data or large programs. It is an easy enough aftermarket add-on so you don't need to order it with the PC.
(just remember to connect it to a fast SATA3 channel - it will saturate anything less)