DIY digital (using a dslr) has the advantage that all the test shots needed are free and immediate, film SLRs can't do it cheaply or quickly (at least, not enough for me to bother).
Pre-built (film or digital) have the advantage that all the nodal point stuff has been figured out in design, all you have to do is mount it level and press the button and you're done.
There's the half pre-built and half-diy automated solutions like GigaPan, but how expensive are they?
Having an all-in-one shot film camera removes all the headaches of stitching, but then you need a huge scanner/enlarger anyway. Depends on the vertical angle of view. If you can get a 360-round-trip in, say, a 6x24cm bit of 120-film with a wide-angle lens then you can at least use an 8x10 enlarger or flatbed scanner. If your lens is narrower and you need a full 2-feet of film to get 360-degrees then there are not many enlargers or scanners on the planet that can handle that without cutting and stitching later.
The biggest annoyance when making 360-degree panos, whether film or digital, is getting the exposure right. Unless you've got a completely soft-box-cloudy sun-free day, then you're going to have major spot blown out and major spots black, even with B+W or C41 film.
Hence I'd definitely prefer a user-selectable model, at least 90/180/270/360 degrees, like a DaYi 67/69/612/617 selectable-back. Even if you're stuck doing the whole roll on the same setting, it's still better than only doing 360.