There is one thing you have to praise JMicron on; they must have one helluva SSD controller sales team. If it wasn't shocking enough to find one of their controllers in the first Western Digital SSD, they managed to convince Patriot that a JM612 with 64MB of cache would be sellable at the 350USD price point. I would have loved to have been around for that pitch.
I think we have hammered the Zephyr enough on performance and you have already written this one off at the current price point. If you are still looking for a drive with this controller / cache configuration, but with a little more studder free firmware, there is the Kingston SSDNow V Series that currently sells at Newegg for 259 or around 100USD less than the Zephyr.
On the other end of the scale, if you can afford to spend a little more money, I found a pretty insane deal the other day at MyDigitalDiscount.com on the A-DATA S596 that uses the Indilinx Barefoot controller and only costs 309.99 USD. This is the lowest price I have seen to date on a 128GB Indilinx Barefoot controlled drive. When we reviewed the drive it shipped with an older firmware, but A-DATA now has the latest firmware on their website and the performance is quite impressive for this amount of money. ADATA has also stated to us that the S599, their SandForce SF-1200 product has an MSRP of only 380 USD in 100GB capacity and at this time is one of the fastest SSDs available on the market.