According to ntpdate's man page, it's considered deprecated, and should be replaced by ntpd -q. Given that, I suggest changing the initscripts Arch ships with ntp.

Advantages:
- we are in line with upstream's intentions
- there is only one place to list timeservers (ntp.conf) instead of two (ntp.conf and conf.d/ntp-client)

Disadvantages:
- the script should be renamed from "ntpdate" to "ntp-client" so that it continues to make sense, which will catch the many users not paying attention
- this new method seems to be a bit slower (10 seconds for ntpd -q vs 2 seconds for ntpdate)

The patch I'm attaching does rename the script, which makes it look longer than it really is. I also have the "-q" flag hard-coded into the script, as without it, there's no point in running it at all.