Not too bad...just be careful to use only one VCO in square wave (that was what the TB-303 had) and only the lowpass setting on the VCF. Granted, the Neutron's VCF is 2-pole, not Roland's weird 3-pole LPF, but in the right parts of the range and with perhaps a tad of overdriving the filter, you should be right in the ballpark. Again, the sequencer is the key here...that odd non-linear glide that the original 303 has is another great example of a "wrong" design doing something "right", sort of like Moog's CP3 mixer.