Slimming the stable.. Opinions and thoughts on bike options

I was always of the opinion that you can never have too many bikes, N+1 and all that. However, got a bit daft really. Up until a couple of weeks ago, the number stood at 6.

Spesh enduro, for general XC/trail stuff
Trek Session, for DH
Carrera vulcan, cheap rigid for riding with the dog, towing my boy in his trailer, canals, tracks etc.
Planet X pro carbon, good weather road rides
Carrera TDF, bad weather road rides, commuting
Carrera Crixus CX, road/off road/trails, anything not too tasking.

I've now sold the Session and the TDF, so stuck with the 4

Spesh enduro, for general XC/trail stuff, will also use this for DH as I used to before
Carrera vulcan, cheap rigid for riding with the dog, towing my boy in his trailer, canals, tracks etc.
Planet X pro carbon, good weather road rides
Carrera Crixus CX, road/off road/trails, anything not too tasking, commuting, bad weather road rides

I'm wondering if I should slim down some more, in order to get more use out of each bike, and to generate some room. I was thinking should I get rid of the vulcan & crixus & replace them with a hardtail 29er, something short travel and quite racey, which would give me

Spesh enduro, for general XC/trail stuff, will also use this for DH as I used to before
Planet X pro carbon, good weather road rides (probably use it for bad weather road rides too, or just stay in..)
29er hardtail, road/off road/trails, commuting, bad weather road rides(maybe not ideal), riding with the dog, towing my boy in his trailer, canals, tracks etc.

I'm assuming that a racey 29er with skinny fast rolling tyres isn't going to be that much slower than a CX bike for the terrain i'm talking about. Bear in mind, i'm not after all out speed / cx racing etc. just for what would be suitable / sensible choices for the stuff i've listed.

Whats your thoughts peeps??