Since you are limited to using Maps in China, you will really be limited to HTTP. This is their answer on the FAQ page .
Why can't I access the Google Maps API from China?
The Google Maps APIs are served in China from the maps.google.cn domain. This domain does not support https. When accessing the Google Maps API from China, replace https://maps.googleapis.com with http://maps.google.cn .
For instance:
https://maps.googleapis.com/maps/api/geocode/json?address=1600+Amphitheatre+Parkway,+Mountain+View,+CAwill become:
http://maps.google.cn/maps/api/geocode/json?address=1600+Amphitheatre+Parkway,+Mountain+View,+CA
The Google Maps JavaScript API can be loaded with the following download:
<script src="http://maps.google.cn/maps/api/js?key=YOUR_API_KEY"
type="text/javascript">
</script>
I cannot comment in terms of reliability and speed, but I think it will be all the same, since Google is still processing it. @Scaisedge's answer can give you your domain change experience.