Ev8r,
I definitely don't know as much as you about any CH47 - VL idea (as I had no clue about it until you posted). I am still willing the bet a Christmas sherry or two that the reason was more like:
Someone e.g. SDSR analyst bloke/blokess: "if we close Odiham could we relocate the Chinny's to VL to save cash?"
RAF VSO: "That's a very good idea, Wing Cdr xxx look into it will you?"
…later that day…
RAF VSO: "Awfully sorry old chap/chapess but funny old thing i turns out that the Chinny's don't fit in the hangars at Yeovilton where our dear friends the RN live, so we'll have to stay here I'm afraid".
(tongue less in cheek) Ships' hangar height is not entirely irrelevant if you can change a head/gearbox at sea. (firmly back in cheek) Further to that I think that CHF would rather change a gearbox outside using a crane in the snow than relocate to Benson!