I am always skeptical about products that promise to repel or deter critters - very few actually do :-) It may be worth a try, however Espoma products are generally limited to the east coast. There are a few garden centers here that sell some of their fertilizer products but I've yet to see any Epsoma bagged soil products available locally. Shipping expenses may well be a limiting factor :-)

Have you considered making or using bulb cages? These are very effective in controlling predation by squirrels (which are BIG bulb problems in this area) and should work as effectively on voles.

I just came across an article in Horticulture mag Jan 08 about using Espoma or PermatTill in creating raised beds and rock gardens.
Never heard of it before.
Have heard of using "quarter-ten" gravel but now can't find any material yards that know what that is!

I DO have MOLE problems majorly!
And am wondering about using this method in some areas.
However, their application method goes against all soil drainage physics. Seems there would be a perched water table.

Also wondering how it improves drainage in clay soil, yet improves water retention in sandy gravely soil!!

Here is a link that might be useful: application instructions