orybrowne,
The OBi should work well for you in Chile. GoogleVoice should work well for you on the OBi although I believe it is recommended that you obtain a 2d separate GV account to run on the OBi because you can encounter problems if the single account is registered on both the OBi and your computer at the same time.
The OBi allows you to setup, in addition to your GV account, a regular (sip protocol) voip account. This is what I would use if you wish to have a Chilean local number. As previously mentioned LocalPhone has Chilean DID's available in 12 cities for USD $10/month, Anveo has DID's in 21 cities for $6.35 or $7.50 per month, and CallCentric has DID's in 12 cities for $8.95 per month. All of these are for unlimited incoming calls without per minute charge. These are local Chilean phone numbers in the listed cities and people can call you on one of these numbers as a local call to them.
The OBi also lets you setup additional outgoing only voip providers if you wish. There are a few providers that offer lower per minute prices to Chilean cell phones than GoogleVoice's 10c/minute. The most reasonable rates I've found to Chilean cell phones are at Future-Nine (2.5c), CallWithUs (2.2626c), and
Voip.ms (3.92c).
I would try out different providers to find the one with the best voice quality and reliability.
RedVoiss is a local Chilean voip provider to also consider, although their web site doesn't seem to indicate that they provide incoming numbers.