I've heard way too many horror stories about the L85.
Dodgey gearboxes (piston & gears), dodgey compatability
Terrible hop
Misfeeding and doublefeeding due to the hop being too long or too short
Poor mag compatability - only guaranteed to work with ICS mags, and they don't do many mid-caps
Electrical contacts in the receiver wearing out
Not the RS dimensions
Proprietary parts in abundance (tappet, hop, some others), ICS made only. Tend to be average quality at best and fairly expensive
Etc.
On the other hand, I know for a fact, that when you get one that comes out the box and just works, they're beautiful and they go like tanks. They're finished brilliantly and generally feel like solid kit. But I can't risk it coming out the box a lemon. Longer barrel and that comfy, warm and fuzzy bullpup feel.
The SCAR on the other hand isn't much in the way of proprietary stuff, it's an M4 set of internals in a SCAR body essentially. Seems to be fairly reliable simply due to the fact that you can't go wrong with a set of internals so commonly used. Lower lemon rate and no totally bizarre issues or confusing compatability problems to knowledge, but it's just not as nice as the L85 in your hands; too much polymer, not bullpup, not enough warm and fuzzy.