If i'm not mistaken, the only restriction will be when it comes to overclocking. Since the new 9-series boards can OC a locked processor (usually unlocked are designated with a "K"), it is looking like Intel isn't releasing "K" CPUs this go around. This means that your z87 will be limited to what it can push via Turbo Boost.
That being said, the 4790 turbos to 4GHZ, which is the same frequency you get from using your board's OC-Genie with a 4670k (though OCG excessively volts the CPU, IMO).
Unless you already bought your g45, I would look into MSI's z97 boards (they have some cool new audio features). If you already bought your z87-g45, then I would go with a 4770k (unless you don't want to OC, then go with the 4790)