I generally avoid FE-only vendors because they tend to ship more slowly; there's no incentive to get out the product quickly if the customer has already released coins and the likelihood of being left negative feedback is low. In addition, most of the vendor exit scams I've seen have been made by FE only vendors.
I do, however, finalize early for vendors with whom I've had a consistently positive experience. This is without the expectation of a cheaper price or extras. I find vendors who allow escrow to be professional and fast, and I feel that rewarding them with immediate money on hand and heightened security is a good thing. Vendors get to avoid both BTC fluctuation and most of the brunt of a market exit scam. Does anyone else do this? Is it a reasonable practice? I've found many vendors to be wonderful people and would like to reward them for their good service. I don't think it's likely for them to exit scam if the majority of their orders are in escrow.
I never FE when not required. Many more vendors have FE scammed than there have been sites that have stolen escrow funds in the time between I've placed an order and released funds from escrow after receiving/testing the product.