Ive owned both the machines you mentioned. *I had the 800 first & replaced it with the Ikon!
The main difference is that internally the Ikon has a stainless steel boiler where the 800 was a thermoblock. *I found the steaming control & capacity to be better with the Ikon. 8-)
A couple of other suggestions if you choose either of these!
[*]Grab yourself a Krups *non-pressurised double basket (around $13)[*]Buy a decent tamper. *I ended up getting one made from Greg Pullman, as the Breville & Sunbeam machines have smaller than normal baskets.[*]I got the Breville grinder free. *Allthough its doing the job at the moment, it is on the finest setting available & if I need to go any finer...Im in trouble! *Do yourself a favour & get a better quality grinder straight off