i have similar... i suppose the bars are thicker than metal ones but we have no problem heating our living room. we do have 3 vents though, which may be important if you only have 2 for a large space?

they need to be strong if they get stepped on, or furniture gets set on them... i guess thats why they are so sturdy looking.

When looking for new Flush Mount Registers, make sure to search for High-Output Flush Mount Registers. There is a bit of additional spacing on High-Output Flush Mount Registers and they typically allow for about 30% more airflow than standard Flush Mount Registers. You can find these in a variety of unfinished wood species like red oak, white oak, maple, cherry etc. so that you can stain them to match your new flooring.