I was thinking that the problem with a dynamic ip is that when it changes you'll need to wait another 2 days (or whatever) to get accepted as a masternode again. But I assume Mr. Spread will make it so that your masternode key is remembered.
I'm testing whether a Darkcoin Masternode actually needs a static IP. Just fired one up on testnet from my laptop. (Using the QT client, georgem!

)
I think that once the masternodeprivkey has been generated, linking the controlling wallet to that 1000DRK vin, that's all the network cares about, if the MN IP changes it should still broadcast itself as a MN and be accepted as one. You shouldn't lose your place in the payment queue unless your MN is offline for over an hour, 71 minutes or something I believe.
I could of course be completely wrong.

edit: OK, fired up the MN, checked that it appeared in the masternode list on another testnet MN I have running on a VPS elsewhere, then disconnected the home MN from one ISP and reconnected via another. debug log shows masternodey activity continuing but masternode list on remote VPS MN still lists my home MN with the previous IP. I will leave it a while and see how it goes. Proof will be it recieving a payment in due course...
edit2: Found this in debug.log:"2015-01-18 19:57:27 receive version message:Satoshi:0.10.17.16/: version 70051, blocks=94034, us=146.156.164:19999, them=108.61.203.206:19999, peer=107.191.48.59:47354" - local MN is definitely still functioning as a MN after the IP switch.
