With time in both the EMB145 and now the MD80 I can tell you I have no reservations when I use the MD80 radar. Yet the EMB145 never seemed reliable to me.
I studied the Archie Tremmel videos, I brought the laminated card regarding beam angle to altitude. I even did the math Archie recommended. Yet almost half the time we'd pop out of the clouds at FL370 and see a different picture than we expected from the radar.
In my opinion the EMB145 radar is essentially a turboprop radar. It works very well until you hit the upper 20s. By the time you reach 350 or 370 it just can't tell you specifics. I saw purple at FL370 once on the EMB145 and it was something that could probably kill you. So it does have its uses even up there. But comparing that radar to the ones in Airbus, MD80s, and Boeing is comparing a C172 to a jet. More often than not in the EMB145 we'd use the TCAS to see what those aircraft were doing and follow them. The EMB145 will keep you out of intense cells but that's about it.