This is going to be a joyless conclusion. The widely available SSDs based on the JMicron controller can only disappoint you with their performance, especially if compared with alternative products. We can only recommend them if your SSD is going to work under read-only loads. The JMicron-based SSDs we have tested are very slow at writing even if they employ SLC memory. Considering that their performance at reading is far from record-breaking, buying a JMicron-based SSD would only make sense if it is cheaper than SSDs with other controllers and you cannot use ordinary HDDs due to circumstances such as a high ambient temperature or vibration.
Otherwise, we’d recommend you some other product, e.g. the Corsair X128 based on an Indillinx controller. Coupled with good firmware, the controller makes this model competitive to the second-generation Intel X25-M under most loads, including random writing, and beats the latter at sequential reading.
Meanwhile, we have already seen hard disk drives with SATA 600 and SAS 600 and now expect these interfaces to be implemented in solid state drives as well. Additionally, SSDs have recently got a strong support in the way of the new operating system Windows 7 which can correctly erase data in flash memory. It looks like this is just the right time for the manufacturers to roll out some seriously updated SSD products!