May i ask where you have bought the MC2 - directly from the manufacturer? And what are your impressions?
I got the boron mk2 from audio arts. It is 0.65 output as opposed to 0.2 for the finish gold and the formula. Also the loading for it is 100 ohms and for the top two is 845. The top two (finish gold and formula) are extremely difficult on phonos, to the extent that you will find many forum reports on the gon of people strategizing their analog chain to fit the cartridge.
I was also advised that the boron mk2 can actually sound better because it has more drive, body, and that balance of tone and body. The top two try to add a beauty but lose out on the body. I was able to verify this in a compare of the boron mk2 and the finish gold.
I would advise not using it on valve phono stages as it can sound colored. All the above aside I found Fremer's review of the Allaerts to be spot on, except that I think with the boron mk2 you will get better body at the cost of a bit of resolution to the finish gold he has renewed.
Audio arts put it on a 300k USD speaker system with expensive FM electronics. He could have put anything he wanted.
Is it my favorite cart? No. But it certainly is an excellent cart for a sensible amount to the extent I don't desire more in a similar sound type (will look for alternate sounds). Also cheap retip and long hours. Trade offs are less flexibility with phono stage and possibly poor service from manufacturer though Anamighty sound in Paris is experienced with Allaerts retips and high quality service (haven't tried their retip myself)