Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
I haven't tried DD-WRT but is it ok to be switching back and forth between OS's? How many flashes can a LinksysWRT54GSv4 take? Has anyone tried both? Which is better?
Yes you can flash back 'n forth. Naturally there's always a chance you might brick the router when flashing firmware....stock or 3rd party. But properly and carefully done....usually it's fine.
I found tomato a little ligther and quicker, DD-WRT has some more features you may or may not use.