I have the original release also. After reading your post I went into settings>about and selected 'system updates' and received the message 'Charge the watch to update to MNC40X'. Pretty cool. I haven't updated it yet. I've never been an AT&T customer. I use Truphone. I'm a bit afraid I'll break something
Haha! Yeah no kidding! I'm sure it won't, you just won't have the NumberSync option.
Samsung S6 Edge+ w/ Urbane 2 & Moto 360 2