I voted for about the same. TPAs can help a collector with a specific piece. JSA caught a wife-signed piece at the National for me that saved me a bunch of $$. If I can't get it signed myself I am willing to lean on a TPA to back up my own research.
TPAs also make it easier to sell. Sorry, but even if they do make mistakes they are
generally treated as reliable by the purchasing public.
What I won't do is purchase items that I cannot research myself unless they are sold strictly for the collectible value [such as a vintage photo or postcard I'd purchase anyway at the price offered]. I looked for a good long time before buying my most recent expensive [for me] autograph and was completely satisfied that the TPA [PSA/DNA in this case] absolutely nailed it before I bought the item:
