Check out the Abus Futura, this a lightweight version of their heavyweight Granite lock.
I've got an Abus Granit Futura 64 U-lock (2010 version). It is still quite heavy at about 900g, and I find it more awkward than my old chain and padlock. So I tend not to use the Abus all that often, and generally only with my most expensive bikes (Raven Tour with Rohloff and perhaps now the RST). The Abus will probably get used on my next long tour, last time I had used an old mountain bike, so I was less bothered about the bike getting stolen.
I have been using the chain (wrapped inside an old inner tube) for over 30 years, it looks reasonably tough, but I once sawed through a link in less than 5 minutes with an ordinary hacksaw, can't remember why. Maybe to replace a seized padlock as the one I have now is more recent than the chain.
I rarely leave my bikes locked up outside for long periods. When I know I will do this I generally use my old 650B bike, which I believe is less attractive to thieves (5 speed hub gears from the 1980's), though it does have a SON dynohub. I have a frame lock on this, which is very convenient for short stops. When I do the supermarket run with this bike, I also use my old chain lock to attach the front wheel and frame to a post or bike stand, plus a very old and very light cable lock to lock the pannier bags to the rear rack. So 3 low to moderate security locks instead of 1 high security lock.
I like frame locks, and have them on the two visitor bikes as well as on my old 650B bike. I'm toying with the idea of getting one for my Raven Tour, to be used for very short stops, like buying bread. I have the Abus Ampero frame locks, in the non-captive key version.
Caveat - I live in a small town in Brittany, which is a low theft risk area.