I haven't noticed any problems with proxy server and Version 10 (I think the proxy server didn't changed).
I always prefer to use VPN tunnel between sites, not 3CX proxy server. There are several reasons for this:
- need for a PC to run it (sometimes this is an issue)
- no way to provide QoS (sometimes this may be very important)
- not possible to run 3CX MyPhone application
- no security (encryption) of tunnel (could be necessary / preferred)
- problems with some phone (Aastra)
Meanwhile I'm quite satisfied with MikroTik routers -- inexpensive (about € 50.-/$70. for RB750GL) and feature-rich, you can easily set various tunnels like pseudo-wire, GRE, PPTP, L2TP, IPsec, OpenVPN, etc., implement prioritization of VoIP traffic, load balancing, etc., even BGP, OSPF support. Normally you have this functionality in routers which are more than 10 times more expensive (Cisco, Juniper, Huawei).
Regards