The DC50 is really a very light duty machine. It is the feebler update of the DC24 but with more built in obsolescence. Suitable for pensioners without animals in a small apartment only. And riddled with design faults; see the link. And the comments.
I have heard from several sources, that those brushroll bristles wear down quickly. That's a shame, because DC50 seems like a decent vacuum.
I can also confirm, that bagless vacuums has lower cfm than bagged ones.
I know this, because I tested airflow with several of my vacuums and bagless vacuums didn't do too well.
For example my Electrolux UltraFlex (bagless) has lower cfm than my bagged Lux Royal D790. What makes this more interesting is that Electrolux has 2100W motor and Lux 1150W and still Lux pulled more cfm. I suspect that it's because of the very simple and straight airpath.