They have a bad reputation for not being reliable.
I tested out the Studio 110, the LD150 (12") and the LD 300 (15").
I really liked the sounds I could dial in out of those Line 6 amps.
I could see myself using the sound in my metal band.
And IMO the Studio 110 is one of the nicest practice amps out there. (There are better alternatives off course).
But honestly, above the 12" combo... I find them heavy. I think the 15" combos and the 2x10" are too heavy.
I would rather go to a Line 6 halfstack then to those combos. (I rather do 2 trips instead of one akward trip with a heavy combo amp.)
What also put me off is the silly layout of controls, and the lights in the buttons.
Too Fisher Price-ey I think.
I love the sound quality... durability, construction quality is something else.

(I have no experience owning a bassamp from Line 6,... but there are many bad reviews on general quality.)
I think Line 6 guitar amps are also really nice.
If it wasn't for them being expensive I would pick up a Vetta head for my guitar.
Line 6 really got to revision their amp series. I hope they will become better.