N66U. Went from 270.26b to 374.38.2.em. Pretty much the same in terms of range and speedtest, which is a good thing.
Hey folks, update here.
First I want to give a big thank you to Merlin. Over the Christmas holidays as I added more new toys to my network I realized again just how important a good router is these days. I am an average Joe and now have 20+ wifi devices, PCs, smartphones, tablets, security cameras, thermostats, smart TVs (boy is that an oxymoron), and streaming devices. I really do appreciate Merlin firmware, it has made my family's wifi life much better.
I got a N66U a few years ago, installed Merlin the day I got it and was a happy camper from the get go. I installed a few updates but stopped and then really stopped thinking about them when the SDK6 driver issues came to light for the N66U.
In terms of my update to 374.38.2.em, initially it looked like pretty similar in terms of range/connect speed. I was pretty excited about that at the time as I expected a downgrade, but had decided to do it anyway on a cold, rainy day out of technical curiosity.
The conclusion I have come to after 10 days is that it really is a bit of a downgrade. Initially most devices appeared to be very similar in terms of performance, though as I have I looked more closely, most are just a bit worse. Not a huge deal, but the real issue I have is that's just enough to push a few borderline devices from acceptable to not.
In my case it really is device dependent. I have a LG Smart TV 20 ft from the router that now lags/buffers when streaming that did not before, yet a WD Live streaming device 40 ft away works just as well as it did before the firmware upgrade. Same with a pretty new 2.4 NIC only PC (ty Dell!), I can now find spots in the house that did not exist before where it is noticeably slower.
So I am going to try the last release of SDK5, 374.35_4. If anyone has a different recommendation I'd love to hear it.
Thanks again Merlin, you da man!