Since I have not yet received my HiFive1, I am using the Arty. Running dhrystone on the Arty appears to be a bit faster (in terms of DMIPS per MHz) than the reported results for the HiFive1. See this link: http://forums.sifive.com/t/poor-dhrystone-performance/233/4. But the Arty apparantly can only be running stable at max. 65 MHz, whereas the HiFive1 can run at much higher speeds: http://forums.sifive.com/t/clock-speed-of-e300-on-arty/289.
Running whetstone (floating point operations), the Arty seems to be much slower than the HiFive1 (again, in terms of MIPS per MHz) : http://forums.sifive.com/t/wherstone-benchmark-on-the-hifive1/262
I don’t have a VC707 (busts my budget), but I would expect it to outperform both in all respects. (At it’s price of well over $3K, it most certainly should!)