You may want to try this version instead, it includes all the fixes and upgrades but retains the range and throughput of previous versions.
http://forums.smallnetbuilder.com/showthread.php?t=18914
I have been using it for the past few days with no issues, but I would recommend to do a full reset to defaults and manually configure your router after doing the above firmware flash.
Specifically:
Unplug any USB devices.
Reboot router and wait about 5 minutes.
Flash the new firmware you want.
Configure the router manually and minimally for internet and lan access. That is, create a router password, a 2.4 and a 5GHz band ssid and passwords and optionally configure the LAN settings (if needed).
Reboot the router, wait 5 minutes and reboot the router once more. This step has helped greatly for stability in my case.
With the above complete, take a backup of your working settings (for this specific firmware) and feel free to experiment with tweaking any settings you think may improve things.
What I change is Tx power to 200mW for both bands and disabling beamforming too.
I recently flashed the latest Merlin build but I am not at all happy with the range and speed. I already downloaded the 374.43_2-02j9527 version but haven't yet flashed it when I saw this post.
Looks like I'll be flashing that first thing in the morning.