I've been running 47074 for almost 2 days on my 1900ACSv1, but with wifi disabled.
I did not have any luck with wifi on my 1900ACSv1 with any release since 44048 - even after resetting both partitions about a month ago. However, I saw your post and enabled wifi again and tested it with my macbook and iphone for the last hour. I had my iphone freeze up twice but my macbook has been working good.
Maybe you could try resetting to factory on both partitions, upgrade both partitions to 47074, reset again, and then type your config in from scratch?
47074 wifi is running great on two netgear r7800s and my 3200ACM. Maybe I'll try resetting my 1900ACSv1 and typing the config in again. 47074 looks like a good release - not sure why I can't get reliable wifi with my 1900ACSv1.