I agree with what Marius wrote.  Those models will perform very well in a network like that.  We use a CCR1009 in our gateway for the 44.137.0.0/16 network (BGP routed on internet) and use it to provide VPN services to users and nodes inside the country, and to feed the radio network as well.  The RB1100AHx4 should be equally capable of that. I would avoid the RB3011, should there be a tight budget or should there be a need for smaller devices at other places in the network it is better to use models like RB750Gr3 or the proven RB2011.

As with any router and in fact with any device connected to internet, you will have to make sure it runs uptodate software (software can be upgraded for free as long as the device gets software updates, which will be quite some time for these models) and also you have to configure it in a reasonably secure way, e.g. make sure the management interfaces (telnet, ssh, webfig, winbox) are only accessible for your own people and not for the internet at large.  This can be done by restricting them to certain interfaces, subnets, individual addresses on internet, and/or by using a VPN for management access.

Keeping the management ports (22,23,80,8291) open on internet has proven to be a recipe for disaster.

Rob