I tend to play things on the line between rock/metal as well. I played Ecstasy amps for better part of a decade. I was not using the 101b though, I was running a stereo rig with a 20th Ann. EL34 and a Classic. I was very happy with my tone for everything I did. That said, I got a JJ due to being a fanboi, then after the JJ came a Slax and the Bogner's had to go...
All of these choices are fantastic amps and I don't think you could go wrong with any of them. That said, you gotta be clear on what you want. Rock/Metal can be a blurry line at the best of times and many of the rock/metal bands cover a wide array of tones, especially the progressive bands.
Ecstasy probably has the most versatility or widest range of tones available especially the 20th ann. as you can go from clean cleans, to mid gain with plexi mode, to high gain. On the JJ, the cleans wont be as clean as the Ecstasy but still very good. You also wont be able to get as much separation between the BE and JBE tones without mods to add gain and volume pots for the JBE mode, which also makes that mode footswitchable and more like a 3 channel amp. With Slax, you wont get clean cleans. You can get pretty clean, but not as clean as JJ nowhere near as clean as an Ecstasy. But you can get amazing hairy cleans up to crunch on channel 1. You can roll back the gain on channel 2 to get closer to mid gain tones, but I find that doesnt sound that good, this amp wants gain, so I tend to use the BE channel as a high gain rhythm channel. Slax channel 3 certainly goes above anything the JJ or Ecstasy can do in the gain department and is a true metal or lead channel.