I work with the SILabs debugger and "real" ICEs in a mixed project.

Today I use JTAG microcontrollers. Why ?....they work and the utility offered is as good or better than many ICE boxes and your entry cost is a $100 or so.
sadly "the utility offered is as good or better" is not so. The one I am very familiar with is the SILabs and compared to e.g. Ceibo it is a nest of bugs. Also, it seems that the people involved with this program are so far removed from the real world that the result does not belong here. Many things that can be done with one or two mouseclicks in a "real" ICE takes 5 or six in the SILabs debugger. The "real" ICE is made to make debgging fast, my best guess is that the SILabs is made to make it "flexible". That nobody need the "flexibility of displaying an int as a char and that this "ability" add 2 or 3 mouseclicks to a regular debugging operation seems to be totally lost on the developers.

Do not read the above as a resistance to JTAG debugging, the idea is wonderful, the execution stinks.

Erik