Silk will last twenty years or more.
Thinner diameter, cuts the wind better,
More supple, lays that dry down so very gently

You do have to dry it after each outing and dress it before. Really not a big deal, both just take a few seconds to do. If properly dressed they will float all day. If you don't want to fish drys, say nymphs or wets, just don't dress it. So no need for a second spool and line. Or you could just dress a portion of the line.

I have fished Sylk and I have no problems with it, some do.

There is a DT5 for sale on the classic fly rod forum right now. It won't last long.