She is VERY GOOD. But Keith was better. Not only did he write the material, but he played "cleaner."
Keith's signature sound was the use of the "harmonic percussion."
For those that don't know the Hammond (and other vintage organs before the use in individual "keyers" for harmonic percussion, let alone digital), there are 9 key contacts under each key; one for each drawbar. When you turn on the percussion (only available on the top keyboard on one of the two sets of user adjustable drawbars), it takes away one of those contacts. The harmonic percussion will only work if that contact on the key played prior is completely broken before the next key is played. If you hold a key and play the next, you will not get the percussion sound.
Similarly, if you don't play "clean" you will not get the percussion because you didn't break that contact before you hit the next key making that contact.
When you listen to Rachel play "Tarkus" on the Hammond C-3 (version with the Moog 3C), you will hear that there is nowhere near as much of the percussion as when Keith used to play it, at least in his better days. This would indicate that she is not playing quite as clean as when Keith recorded the original.