During our last network refresh, we did a wholesale forklift upgrade from Cisco to an entire Juniper network infrastructure, including Juniper SRX router/firewall/IDP, EX Series switches, and QFX Series core switches. The entire process took over two years to complete, but once it was completed, we were extremely happy with the Juniper equipment in terms of costs, performance, maintenance, and the ability to function as we needed.
Third-party support for Juniper is a lot less than Cisco. This is no surprise, but a definite consideration if you are expecting to use a lot of third party support. In my guesstimate, for every 100 Cisco shops, you will find one Juniper shop.
Three to five years.
JTAC (Juniper Networks Technical Assistance Center) is just okay for technical assistance. However, if you are used to Cisco TAC responsiveness, you will need to adjust your expectations with Juniper Networks TAC.
I could normally fix my issue with Cisco on the first or second call, speaking with the first Cisco TAC engineer (Tier 1) that I spoke with. Juniper Networks TAC is just as good, but in my experience, it takes about two to three times longer to get the same results. It is not unusual to require escalation before the issue is resolved. Juniper simply does not have the depth and number of Juniper experts as Cisco.
We were able to lower our overall operating costs over a three year period by 25%, mostly recovered from maintenance/support costs.