Hey Sam,
All end users can ping each other, but the SRX's themselves cannot ping end users on the other side of the VPNs.
If I log into the SRX for end user 1 and try to show route to end user 2, I see this:
inet.0: 21 destinations, 31 routes (21 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.10.0.0/16 *[Static/5] 11:45:32
> via st0.0
[Static/5] 11:45:32
> via st0.0
This is correct as st0.0 is the VPN interface on the SRX to get to that 10.10.0.0/16 network on the other side of the VPN, but I still cannot ping anything on that network.