I would suggest z-wave micro controllers, one relay for the on/off only circuit, and two dimmers for the others.  If you associate them with the right switches you could also operate them as 3-ways plus have local control.  The micro receivers are very small, about 2" square and about 3/4" thick so you can put them almost anywhere.  We sell all these products in our stores so if you are interested, please contact me.  I would recommend a bit of testing with the micro dimmers first as not all dimmable led's work for all dimmers.  It sometimes depends upon brands in this day and age, as you found out with Insteon.

Hope that helped!