Your router is ddwrt compatible so nothing ventured, nothing gained. dropped internet can be related to new firmware upgrades or just the fact that you have been running the same settings for so long they have become corrupted in the router's ROM.
Before deciding to flash a different fw, I would do a hard reset of what you have. Reconfigure everything and see if that helps.
If no success, I'd go back to the last fw version and see if that is any better and if not then reinstall from scratch the current factory fw version.
The current ddwrt fw version is not always the best. You'll need to read the forum for your router to see what most people have decided is working well for them.
Before flashing ddwrt, make sure you know exactly how to do that and revert back to factory fw if need be. Some routers even have a means of reviving a bricking that does not entail throwing the router at the wall. Make sure you have all the files and software you need to install ddwrt, revert to factory and unbrick (if necessary) on your HD before you begin.
Learn what a 30-30-30 reset is if you don't already know. Resetting your current fw should be enough fix the problem unless the radios are dying due to age and operating at high temps for a long time. Then a new router is the way to go.
The difference in regional fw is primarily regulation compliance due to signal strengths and radio interference considerations. The core fw functions are usually the same regardless of region.
Good luck. If you are successful with ddwrt, you'll really like the extra config control you have. Don't be tempted to set your wifi strength to max, you could hasten the burnout of your radios.