Ongoing neck risks?

[OakLeaf]

How are they on the lumbar spine, though? Seems like it would be really bad, between the seat and not being able to extend your hips?

[TsPoet]

How are they on the lumbar spine, though? Seems like it would be really bad, between the seat and not being able to extend your hips?

You've got to get a seat that fits, but I think that's easier than it is for DFs.
There is something that some get termed recumbutt - which I suspect is a lumbar spine issue. It is (almost?) always cured by a more reclined seat. But, then you get neck issues... but you can easily get a neck rest. Just like DF, you have to find what fits you and works for you. It's easier to do with a recumbent than a DF, though.
On my performance bent, I have a somewhat reclined seat and a neckrest - the combo is wonderful. Fast (for slow old me), but comfortable.
On my commuter bike, I have never had any issues with the comfy seat and recumbutt and my seat is upright enough not to need a neck rest.
Other than recumbutt, I've never heard of back/butt/neck issues on a bent.