I have never heard anything from tylermckee (regarding his crusher) and I have nothing better to report than what I have already posted. In summary of my experience with MB I would say that the customer support is VERY poor and production rates are nowhere near what they claim. It is safe to assume that they would argue that the material is different (MB's production rates are based on concrete) and my feed size is too big. In fact this is what they are telling me now. To that I say that I get the same production rates when crushing concrete as I do most of my rock. Rock is usually harder than concrete and therefore should crush faster (will take less impacts to reduce the material to the size that will fall through the crusher). Dirt, especially if moist or wet, will reduce production considerably. As it relates to feed size the only production reduction I see is from jamming and hot stalling. This definitely makes a difference but I still have this happen when feeding smaller rock too. Regardless the salesman told me (before I bought the crusher) that you can feed any size material that will fit into the opening. Now that I have purchased it they are telling me to feed 10" minus. I am usually trying to make 3"- so that fits into the standard crushing rule of thumb which is a 4:1 reduction ratio (a rule that I have since learned). THIS IS NOT WHAT THEY SAID PRIOR TO THE SALE! They have yet to come out and verify flows and pressures (though I have done so several times-myself and with other mechanics) nor come see what is happening for themselves. They have made repeated promises to do so but never do because they are too busy trying to sell more crushers to others. They don't say that in those exact words but what else would it mean when they say that they are really busy getting ready, being at, or gearing down from one show or another. I've had this crusher for over 2 years....That's a lot of time to be able to make time to support a customer. Even if they put the customer off to go do trade shows. I'm not exactly sure what difference it will make anyway....They don't really have anyone there with much crushing experience anyway (other than when they have been around others who use their product or limited experience with demos). Initially they were pointing the finger at my Cat 315. Not the fact that it is really too small for the BF 70 (they are actually the one who recommended that I mount the 70 to the 315) but the fact that, in their experience, they have the most trouble trying to set their attachments up on Cats than any other brand. Ironically I get the same results regardless of which excavator I mount the bucket to ('03 Cat 315CLC or '17 Deere 245GLC). The only good news I have about this is that (based anecdotally on the opinion of the friend who recommended MB to me (very early version BF 120 mounted to a Cat 330), another contractor who I was introduced to by MB (BF 90 mounted to a Deere 450) and from tylermckee above (BF 120 mounted who knows what) the reports on the larger units are that they do not seem have the same issues. BTW, I would love to be wrong, or proven wrong, about this. Not the reports of larger units having more success/less issues but rather that MB could help me figure out why the unit that I bought is not meeting my expectations in durability, production and post-sale support. Expectations that were set, in part, by them.
As it relates to the Xcentric I have no clue. I would like to try one but have yet to see one in my area. I can say that the Xcentric ripper does not seem to work as claimed in the limestone that we have in my area. I have talked to someone local who has purchased one (ripper) and he said it works good in sandstone. I'm not sure how much presence/support that Xcentric has in the US anyway. To my knowledge MB has been in the US market the longest and their support/presence leaves a lot to be desired (if that says anything about the others). The other major player (in US anyway) is the Hartl. I've not heard to much good about them either (admittedly all rumors and hear-say) except from Mr. Hartl at Con-Expo.
I think that a couple of things (though maybe obvious to some) are worth mentioning here. Salesmen generally say whatever they think will get them a sale (may not apply to all salesman-use your gut instincts and do some homework before you buy). Crushing is not as easy as it looks in videos. There are a plethora of things that will effect production rates and/or costs. Talk to as many people as you can (especially those with crushing experience IN YOUR AREA AND/OR WITH THE MATERIAL YOU ARE TRYING TO CRUSH. Know that any issue a dedicated high HP crusher (stationary or mobile/track mount) may have, or most circumstances that may effect one, will be exponentially more difficult for a relatively low HP crusher bucket to overcome. I hope this helps. Best of luck to you and please report back if you end up getting one or find any info that would contribute to this thread.