7 Pro sounds noticeably better than the the PF500, as it should, but I stick with the PF350 for my lightweight rig needs because I just don't need a 7 Pro. They all have a sound reminiscent of each other (some call it the "Ampeg" sound
), but the 7 Pro sounds bigger to me.
The SVT 3 and 4 Pro are traditionally built hybrids with a big iron power transformer, and while they don't sound identical to either the lightweight designs or the all-tube SVT's, they have a sound that's best described as a cross between all-tube and traditional solid state. They lean more toward the solid state sound, but they do sound quite good to my ears, and some like them better than the micros or the all-tube amps. And of course, there's the tube SVT's...no introduction necessary
The Pro Neo cabs are made in the US and have neo speakers. Have not played them, but the rap I've heard on them is "sounds like Ampeg cabs, but a little tighter and cleaner."