good quality KVM boxes have microprocessors and provide full and full-time hardware emulation so it's not an issue with those. it's also why they cost more.
remote desktop is all you'll need for use with a server. don't waste money on a KVM just for that. you can always plug a keyboard in if you ever need to get into the mainboard or RAID bios for anything. and that shouldn't happen too often. you can also set things up so windows server tries to do a soft shutdown if you hit the front panel power switch so you don't really need a keyboard to reboot it either. as long as your server isn't something like 10 years old you should be fine.
most system boards also aren't fussy about having a keyboard attached anymore. or not from my experience anyway. you may need to fiddle with BIOS settings depending on what you have. but with all the headless home servers being made from old PCs that's a good thing.
sorry I'm rambling. i'm at work and alternating between you and a webserver update while eating a truly horrid vendy sandwich for dinner.