RouterPro is just an optimized version of OpenVPN. It is Astrill's proprietary protocol with Blowish 128-bit encryption. Apparently it is also good for countries where OpenVPN protocol traffic might be shaped. I can confirm it works better in UAE than standard OpenVPN.
I have been looking for alternative backup to Astrill but all of others VPN just don't come close. Also it's funny how negative press Astrill got recently, have you noticed they are not listed as a top VPN providers on "affiliate" based websites? The reason for this is that Astrill dropped their affiliate program and hence the recommendations disappeared lol.
Anyway, when I lived in Singapore:
RouterPro UDP on Singapore 1 (USA):
CPU 100% bottleneck.
OpenVPN on my Mac Pro on Singapore 1 (USA) server:
My ISP speed 200/100 was bottleneck here
Later my ISP upgraded everyone to 300/300 symmetrical and believe it or not, I was maxing this out via Astrill. I could actually download files with speed of 36 MB/s, something I wasn't even able to hit with direct connection.
I have noticed that RouterPro speeds via router obviously depend on the location and latency of the server. Normally it doesn't make much sense for Singapore based customer to use Singapore based VPN server, as the VPN is mostly used to obey geo-restrictions to watch UK/US television. Why it did make sense is that Astrill has server in Singapore with virtual US IP address, which means you connect to the local server and get US IP which allows you to watch US Netflix etc.
Don't expect the same speeds on RouterPro where the latency is higher. I am in UAE now, connecting to UK servers which are the closest, most sensible options to use. With latencies of 120ms I am getting around 45 down / 15 up using RouterPro on Merlin 378.50 and my ISP speed is 100/20. I still think it's great.
Based on my research the only other VPN service with proprietary protocol is VyprVPN but haven't tested them.