Since it's only for the control of my computers, I don't consider the permanent installation of RDP/VNC software intrusive - how would I get the other end to click on the non-existent keyboard to download transient software anyway?
I also don't think it's intrusive for computers you have overall supervision, (or in the case of relatives, "Technical Support"), over across a WAN/VPN.
I do think it's intrusive if you have to rely on an internet connection, as you do with LogMeIn, TeamViewer and, as it now seems, SRD, etc to a an arbitration server not under your control, (this includes the assumption that you'll always have a connection to it), when it's not necessary.
So it's back to finding the perfect VNC server/client or read up a bit more on getting RDP via HTTP to co-exist peacefully with the other servers running.