I haven't seen very many Escient reviews that talk about audio quality from a critical perspective. Their primary focus seems to be on convenience. You insert the disc and it is ripped and tagged with little input needed.
One catch for me would be the Gracenote CD database they use for tagging. This works pretty good if you're you're doing the popular CD releases. It'll have no problem tagging an Eagles album for you. However, as you get into obscure stuff (i.e., just ripped a Lydia Ruffin album the other day to my server which Gracenote is clueless about) you'll need to be manually managing that stuff anyway.
Escient also gets a pretty good price tag for convenience. The MX-531 (500 GB drive) looks to be about $4,000. That's not inexpensive for a device that the one or two reviews I've seen paint as having fairly run-of-the-mill sonics.
I went the Squeezebox 3 route. $300 for the SB3 and a run-of-the-mill computer with a 500 GB drive (easily under $1,000) will probably equal the Escient on both sonics and storage. Add a decent DAC to the mix and you'll have outstanding sonic performance for half the price of a MX-531. You'll also have more flexibility for expansion and customization, though it won't be a one-box solution. I don't consider the learning curve for a SB3 setup particularly hard if one has any basic computer literacy. The SB3/Transporter also has a large and devoted following so there is a good track record of acceptance and experience in the hi-fi community.
Ultimately it'll likely depend on your preference. If you like to tinker a bit and value flexibility and performance, I'd guess you'd ultimately be happier with a SB3/Transporter. If your music is more mainstream, cost is not an issue and convenience paramount, then you'd want to look harder at the Escient solution.
