@frankthetank727, you can totally replace the MXR with the B7K. But as rockdoc stated, you may want to give it a couple months and wait for the ultra. It'll have even more EQ to help you along.
I can't say I know all the EQ points of both the MXR and the B7K, but the MXR may or may not have a little more tweakability to offer. I'm really not sure though. They could be about even for all know. But the B7K does indeed have a baked in flavor. I think the MXR would be more vanilla or maybe ever transparent. Again, not sure. I've never worked with it. My guitarist just got one of those and he engages it when he needs a little boost in certain areas when he's using a certain fuzz.
But anyway, for what you want it for, IMO, the B7K would be grand for it. It has a flavor and I for one love it. It's the basis of my overall tone. It can and will give you EQ, tone shaping, voicing options, drive if you want/need it, boost, and it adds clarity and dimension to your overall sound and tone especially with your dirt pedals. To me, it's ideal. But it's not for everyone. It's also not an all inclusive metal machine. The EQ is really quite versatile. You add the voicing switches, and you have yourself a mighty versatile and broad ranged EQ/preamp. It is capable of doing vintage bass tones to prog to blues to metal and all in between.
There are so many sounds in this box alone it's nuts. I'm very excited for the ultra too. I can hopefully snag one in the spring. It's gonna be sweet!!!