Good news!
The ping latency is fixed in 10.9.2 Beta 2
Ping after 10.9.2 beta2 install
64 bytes from 192.168.178.1: icmp_seq=103 ttl=64 time=1.837 ms
64 bytes from 192.168.178.1: icmp_seq=104 ttl=64 time=0.982 ms
64 bytes from 192.168.178.1: icmp_seq=105 ttl=64 time=1.616 ms
64 bytes from 192.168.178.1: icmp_seq=106 ttl=64 time=1.611 ms
64 bytes from 192.168.178.1: icmp_seq=107 ttl=64 time=1.607 ms
64 bytes from 192.168.178.1: icmp_seq=108 ttl=64 time=1.699 ms
64 bytes from 192.168.178.1: icmp_seq=109 ttl=64 time=1.611 ms
64 bytes from 192.168.178.1: icmp_seq=110 ttl=64 time=0.916 ms
64 bytes from 192.168.178.1: icmp_seq=111 ttl=64 time=0.963 ms
64 bytes from 192.168.178.1: icmp_seq=112 ttl=64 time=1.842 ms
64 bytes from 192.168.178.1: icmp_seq=113 ttl=64 time=1.117 ms
64 bytes from 192.168.178.1: icmp_seq=114 ttl=64 time=1.277 ms
64 bytes from 192.168.178.1: icmp_seq=115 ttl=64 time=1.766 ms
64 bytes from 192.168.178.1: icmp_seq=116 ttl=64 time=1.807 ms
64 bytes from 192.168.178.1: icmp_seq=117 ttl=64 time=1.841 ms
64 bytes from 192.168.178.1: icmp_seq=118 ttl=64 time=1.548 ms
64 bytes from 192.168.178.1: icmp_seq=119 ttl=64 time=3.052 ms
64 bytes from 192.168.178.1: icmp_seq=120 ttl=64 time=1.556 ms
64 bytes from 192.168.178.1: icmp_seq=121 ttl=64 time=0.922 ms
64 bytes from 192.168.178.1: icmp_seq=122 ttl=64 time=1.662 ms
64 bytes from 192.168.178.1: icmp_seq=123 ttl=64 time=0.942 ms
64 bytes from 192.168.178.1: icmp_seq=124 ttl=64 time=0.818 ms
64 bytes from 192.168.178.1: icmp_seq=125 ttl=64 time=0.918 ms
64 bytes from 192.168.178.1: icmp_seq=126 ttl=64 time=1.293 ms
64 bytes from 192.168.178.1: icmp_seq=127 ttl=64 time=0.892 ms
64 bytes from 192.168.178.1: icmp_seq=128 ttl=64 time=1.311 ms
64 bytes from 192.168.178.1: icmp_seq=129 ttl=64 time=0.981 ms
64 bytes from 192.168.178.1: icmp_seq=130 ttl=64 time=1.631 ms
64 bytes from 192.168.178.1: icmp_seq=131 ttl=64 time=1.777 ms
64 bytes from 192.168.178.1: icmp_seq=132 ttl=64 time=1.657 ms
64 bytes from 192.168.178.1: icmp_seq=133 ttl=64 time=2.430 ms
64 bytes from 192.168.178.1: icmp_seq=134 ttl=64 time=1.103 ms
64 bytes from 192.168.178.1: icmp_seq=135 ttl=64 time=1.693 ms
64 bytes from 192.168.178.1: icmp_seq=136 ttl=64 time=1.819 ms
64 bytes from 192.168.178.1: icmp_seq=137 ttl=64 time=1.872 ms
64 bytes from 192.168.178.1: icmp_seq=138 ttl=64 time=1.030 ms
64 bytes from 192.168.178.1: icmp_seq=139 ttl=64 time=1.789 ms
64 bytes from 192.168.178.1: icmp_seq=140 ttl=64 time=0.910 ms
64 bytes from 192.168.178.1: icmp_seq=141 ttl=64 time=0.785 ms
64 bytes from 192.168.178.1: icmp_seq=142 ttl=64 time=0.829 ms
64 bytes from 192.168.178.1: icmp_seq=143 ttl=64 time=0.749 ms
64 bytes from 192.168.178.1: icmp_seq=144 ttl=64 time=1.085 ms
64 bytes from 192.168.178.1: icmp_seq=145 ttl=64 time=1.221 ms
64 bytes from 192.168.178.1: icmp_seq=146 ttl=64 time=1.052 ms
^C
--- 192.168.178.1 ping statistics ---
147 packets transmitted, 147 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.749/1.656/3.196/0.435 ms
I have made sure that there is absolutely no other network activity in background.
The Broadcom version is now Broadcom BCM43xx 1.0 (6.30.223.154.62). With 10.9.1 it was Broadcom BCM43xx 1.0 (6.30.223.154.45)

This means the ping latency was indeed a bug and no feature. I can't comment on other problems like wifi drops as I don't suffer from these.