It's a miracle!
Sorry, haven't seen any half-X with halfling nor gnome, don't expect them to be able to procreate unlike the breederfolk, I mean humans. But back to a more serious answer.
But since "jovial" is part of my main descriptor about halflings, the Whisper Gnome seems in the other direction. (Everyman, community-focused, and hospitality are other parts of my default views on halflings.)
I do think it would be more gnomish - of the two they are the more "magical" of the races on some arbitrary scale I made up, and half-breeds seem to go in that directions - it's half-elves, half-ogres, half-dragons, half-orcs, not half-humans, half-humans, half-humans, and half-humans.