I haven't had any issues with igniters. My bluestar is about a year and a half old. Even if they fail, it's relatively inexpensive and very easy to fix.

Not sure about the grill/griddle will fit on the RNB. I'm hoping it does though.

I would agree on the igniters, just be cautious when you are cleaning not to get the sponge or rag caught on them and shouldn't have any issues. I am just over 1 years of using our range top (36") and no issues at all with them.

I also do not know about if the grill/griddle will fit a RNB, sorry.

phil