I have an Ameritron AlS-600 amp and I like it very much. My only objection is that the linear power supply  has quite a loud whine which can be heard on the air in SSB mode if your signal is good at the receiving station. I read in Ehams where a ham changed the fans to get away from that noise with some success. Placing the amp on the floor in the corner helped somewhat and if you have a nearby closet or large cupboard, it would help to put the power supply in there. The amp itself doesn't have that whining sound. I also constructed a kind of chimney, two feet square and four feet high made of acoustical tile and put the power supply in the center of it. That helped a great deal. If you use earphones of course you aren't as likely to be bothered by that monotonous whine. On the other hand, you may not mind the background noise. I just wanted Frank to be aware of the problem before he makes his decision to buy the ALS-600. Incidentally, MFJ had no solution to the noise. 

Bob K8MXC