Here is some of my experience. I have Control4 in my house and I have had very good luck with it but found a dealer who allowed me to install the devices myself and then he added them to the project. After that I took care of my own system with Composer HE. This has been a very good solution for me but it is more expensive than the other options you mention. If you are sold on C4 you might want to see if your dealer would work with you so save costs if you can install the devices yourself.
For a friend that wanted basic lighting control and control for a small entertainment center, (TV, RCVR, blu-ray etc) that could easily be taken with you I tried both Insteon and Z-wave. I tried Lowes IRIS (z-wave/zigbee) and it worked very well and the devices are reasonably priced but hated the fact that in order to just do basic scheduling required a $10/month. I also found the scheduler to be very cumbersome in that it was device based instead of schedule based. By that I mean you had to create separate schedules for each device even though the schedules were the same as opposed to creating a scheduling and assigning devices to that schedule. Decided the monthly fee was not worth it.
Next up, was insteon and I was somewhat familiar with this because I am old timer and used x10 way back. We needed to keep the system down in price and the goal was just about 7-10 lighting control devices so I went with a Smartlinc instead of the more powerful and robust ISY99i so if you go this way I would highly recommend going with ISY. This was installed in a small house around 1600 ft. and was very inconsistent and unreliable, sometimes all the lights would come on and go off on their normal schedule but many times they would not and it would be different lights each time. If it isn't reliable it isn't for me. I also tried troubleshooting making sure the inconsistencies weren't due to the dual-phase issue on the electrical etc. In the end, with the instability and the hassle of configuring the device links I chose not to keep this solution. In saying this adding devices is much easier using the ISY99i and may be more reliable so don't rule it out completely based on my experience.
Next up, Z-Wave with Micasaverde Veralite. Did some research and looked at the information provided on the Micasaverde website so had some idea about configuring this before I got it, however I have experience with C4 so wasn't worried about this, however, it isn't necessarily easy to use at first if you are inexperienced with this type of device but if you can spend just a little time with it you won't find it daunting at all. I had all my devices added within 15-minutes, had all my schedules/scenes defined within a couple of hours and did it a device at a time at my house prior to installing at my friends. Once I took it to my friends we registered the device plugged everything in and it has worked very well and consistently. I downloaded a very easy $4 iphone app to give me individual light and scene control and it works very well. I purchased an outdoor module to control outside lights, and had it added to the system and an existing schedule in less than 5-minutes. I programmed lights to come on in the morning to help awaken during the weekdays and since this last week was holidays, have kids at home didn't want the schedule to execute this past week, so I added a virtual switch, and when you turn this on, I wrote a bit LUA scripting to prevent the schedule from executing when the lighting was on. Turn the virtual switch off and the schedule will run and turn the lights on. My point is you can do some very complex things with this device with a bit of research. So far I'm keeping this one. I much prefer Z-Wave to Insteon, easier to configure, much faster response times, and more reliable. Again I say this using the Smartlinc and not the ISY device for Insteon.
Now to your IR control of your home theater devices. In this same friends house we installed RoomieRemote with IP2IR device and this works awesome, is easy to setup/configure and anyone can use it, it is so intuitive, and let me tell you the person who is using this was remote challenged but not so with Roomie. Roomie also natively supports the Veralite controller as well, however, I have not set this up yet, plan to do that tonight. I do believe veralite can also be configured for Home Theater control with additional hardware but chose roomie over the added complexity of going with veralite.