First, regarding the lighting system choice, there aren't many DIYers that are able to implement a hard-wired system. So even if the OP does implement a hard-wired system, he won't have the community support that really allows us to get the most out of a system and generally for many DIYers this becomes a (partial) hobby.
Sorry this is long but it goes through my mental process of choosing a lighting system and speaks to many of the things Lou mentioned.
I'm a DIYer and I was at the OPs point not so long ago. So I'll explain my thought process. I need a new home security system so I'll research the options. Oh, there's this great community at Cocoontech that does this cool automation. Ok, well I need a lighting system so let me research the best ones. Oh, I'm reading that people are having problems with Insteon, Zwave, UPB, pretty much every system out there has had one or more individuals with problems. Oh, I don't want that, I want something robust to run the lights in my house. Oh well let me look at hard-wired because nothing is more robust than that. Oh, you have to have a special wiring structure for that and my house is already built. Ok, so hard-wired is out for my situation. Ok, so lets look at some of the expensive ones because they have to be better right? Crestron is just damn expensive so that is out. Control4, while still being expensive, seems to have some good integration with some nice lighting choices. What do you mean I can't get access to the software and make changes myself. I'm not going to pay several hundred dollars a pop for a guy to change something minor on my system, no way. Dang, there are some people that were burnt by Control4 and really weren't happy after dropping $10K plus. OK, what other options. Main three are UPB, Zwave, and Insteon. Zigbee is still a little fractured (multiple profiles) so that is out. Insteon seems to have too many quality issues over time and we are beholden to a single company. Zwave seems to have issues for some people, especially with larger implementations. UPB seems to be pretty solid for the people using although some people had special situations that caused UPB not to work. Ok, UPB would likely be robust in my situation. Those are my switch options, really? Oh and those are the same switch options for the past 4-5 years. That's disappointing. Ok what else. Lutron RadioRa 2. That looks good but it's another closed system where you can't get the software. Well, actually you can get the software but you have to jump through a couple hoops and take some training courses. That's not bad. Research shows RadioRa 2 being very robust with the only major DIY complaints being hoops for software and expense. Well, it is expensive but they make solid switches and the options are much more elegant and up to date than other options available to the DIY community. Ok, let me take the training and see what I think. Liked the training and like the system even more now. Ok, I've finally chosen my lighting system...now what home automation package should I purchase? .....
Now regarding maintainability, if I mention RadioRa 2 or a hard-wired Centralite system, a knowledgeable person (professional) would have a good understanding of the equipment involved and a good starting point of figuring out the system. With a Zwave or UPB based solution you have to ask many more clarifying questions (controller? brand of switches? Etc) before a pro would understand what is involved with supporting a homeowners solution. I'm not saying one is better than the other just pointing out this fact.
David