Sounds like I'm doing something similar. I have a Retina MacBookPro and I connect that to a 30 inch Dell and a 27 inch iMac in Target Display mode. This gives me 3 monitors to work with. I was on Mavericks all day today. I didn't have any problems that caused a reboot or anything like that.
However, I HATE the new multi-monitor "improvements". Having each monitor an independant space doesn't work for me. I wish we could pin a monitor and group monitors. Also on occasion I will extend a window so it stretches to a second monitor. You can't do that with the new improvements.
I like to set the middle monitor for designer, the left for client and the right for browser / server console. Pretty focued... then I'll swipe to get to a different desktop on all three screens to get to personal email... or skype or whatever. Maybe I have another desktop for NotesIn9 stuff... With the new "improvements" to multi monitor I'd need to swipe each screen individually. yuck. I'm really happy the left it an option to disable the new stuff.