im pretty sure the update nag is normal on any system since we're on a low sysnand.....i had the nag before doing all of these today..just ignore the update nag on your SYSNAND 4.X and you can safely update your EMUNAND with rxtool (again do it in RX-E NOT RX-S)and yes i downgraded using the...
http://gbatemp.net/threads/how-to-play-legit-7-x-encrypted-cias-without-gateway-mt-card-4-1-4-5-only.383990/
that's what i followed..it worked flawlessly for me, i was already on 4.2 sysnand to begin with...now i can play my legit MH4 cart without me getting tempted to update my sysnand...and...
First of all thanks to Roxas75 for making this wonderful tool you rock buddy!! keep up the awesome work!...i can now play MH4 with my cousins while staying on a low sysnand (i just made an account just to thank you man!)