The LX20 is a nifty light. I think it was the first awesome LED light that DR made, and it kicked off their next generation LED lighting strategy.
Of course it's not the brightest, but brighter lights like the HP50 come at the expense of burn time, and handheld lights only fit so many batteries. I run my HP50 on medium a lot of the time, which is similar to LX20 on high. When I want bright and long, I have an EX35.
LX20 is not super unwieldy as a backup, similar to the old 3C backup lights. Generally people don't want to drop $1k on backup lights when they start, so they invest in a primary light and then get some $100 backups. But eventually most of us upgrade our primary lights and then--the handheld primaries actually can be used as backups. You don't see many people stuffing an old canister light in their pocket for a backup.
My 12W Salvo canister LED, which was the cream of the crop when it came out circa 2009, still works great. Haven't used it a single time since I got an LX20.
So the LX20 is a great light to start with, and a pretty good light to have around in general, so I'm sure you will be very happy with it.