There is also little or no extra functionality; a G1000 basically combines a GNS530 with a bunch of engine instruments.
A bit incorrect there IO540, the G1000 has got unbelievable functionality and has a solid state reference system so no gyros to worry about. I have nearly 200 hours behind the G-1000 in the last 3 months and I think it is superb, it massively reduces workload especially under IFR.
It’s going to be installed in a number of business jets in the coming months/years and some of the features are unseen at present due to a lack of currently affordable (GA) auto flight technology. Expect to see coupled auto throttles and CDU's in the not to distant future. I do think they take time to get used to...I find the VSI doesn’t "get my attention" but that’s probably a personal thing and the altimeter flashes if you do start to deviate from your altitude anyway.
I cant comment on the connections behind the panel as im no engineer but obviously it is something that will have to sorted if the system is to used in commercial operations (and I have had an intermittent fault which was blamed on...guess what...moisture!
).