I think the Basic 7 is going to cost more only because it is a collectible. M-INFI, is nearly as good as INFI almost no difference and the Basic 7 is one nearly indestructible knife. It took Cliff S two years of overabuse even for him to break one and that was after he machined it thinned it out and beat it to hell. Most knvies would have given up the ghost in a month of that kind of abuse.
Having said all that the Rattweiller is made of 52100 with more of one of it's standard elements. The Rats are awesome knives from the way everyone talks, so I think it comes down to which one you like better, more than which one is better.