I think it depends where you are looking--I've looked at both FHR and Visa Signature options in a few cities lately, and while Visa came up empty some places (Manila, for example) they came up with as many or more options than FHR in others (Vegas, Hong Kong).

I agree that the Visa benefits are not as extensive as the FHR benefits, but that can vary somewhat--at many properties, the biggest FHR benefit is a $100 spa credit, and if you weren't planning to use the spa, that isn't necessarily all that valuable. Especially in a city like Vegas where many spa treatments cost more than $200. The Visa Signature program also promises always to offer you the lowest available rate (excluding special discounts and the usual exceptions), which can sometimes also be useful--I have seen cases where the prevailing FHR rate was substantially more expensive than the rate available through the hotel itself without FHR benefits.

I used the Visa Signature benefits at the Jamaica Inn in Ochos Rios, Jamaica earlier this year (I was attending a wedding there, and it happened to participate in Visa Signature but not FHR, so it was convenient). I can't say it was a great experience--most staff at the hotel seemed to have no idea what I was talking about when I asked about it. Eventually I was able to get through to them, but they said they had been booked so unable to upgrade me (wasn't sure I believed that). I did get the $25 room credit, and the breakfast, though they were very strict that it would apply only to their set continental breakfast, and could not be used as a value deducted against any other breakfast option.

I have a booking coming up soon at Aria in Las Vegas, which I will report back on (would be useful if we could get a thread going like the extensive and detailed FHR one...). I'm booked on the $100 resort credit offer that escog wrote about earlier, which certainly makes the Visa program more competitive with FHR for that particular property among choices in Vegas.