First, you should understand that Control4 and Indigo are targeted to two completely different markets. Control4 systems are professionally installed and maintained with little or no direct configuration done by the end-user. The are also significantly more expensive and generally sacrifices end-user development, modification, and extension. So, these systems are generally sold as packaged solutions including all the parts, programming, etc.
Indigo is targeted at the do-it-yourself (DIY) market - where there are few installers and users are actively encouraged to develop and grow their systems, adding components as the need arises. A home automation system built by the user is significantly less expensive but requires more skill and patience to develop and maintain. DIY products such as Indigo and INSTEON, etc., are sold as components to build your own custom solution.
So, with that in mind, on to your questions:
1) Indigo can't directly control your security system. A plugin could be developed to interface with your system if it has a serial or network-based connection and available API. Our
Plugin API has already been used to develop connections between
Honeywell/Ademco VistaICM and
DSC alarm panels so it's definitely doable. You just need to know Python or find someone to develop the plugin for you.
2) AV Control is possible using the Global Caché hardware and one of the Indigo plugins (
here and
here). There are also some users that have used the iRed software with the IRTrans hardware and used
AppleScript to bridge the two.
3) INSTEON, like any power line carrier technology, can be effected by signal noise. The use of filtering devices on problematic devices will almost always solve problems although it can sometimes be a bit time consuming to find the source of signal issues. INSTEON isn't effected as adversely as, say, X10 because the protocol has retry, acknowledgement, and routing/hop counting built in. Many INSTEON devices are also now dual-band so they use both the power line and RF transports - which also increases reliability (an advantage over RF-only technologies like Z-Wave and Zigbee).
So, I think the first choice is this: do you want a system that's installed by a professional, maintained by someone else, but also gives you a single place to call when something goes wrong? Or do you want to develop and control the growth of your system yourself using building blocks from different sources?
This is the most important decision that requires careful thought, IMO.
