Alright! Thanks guys, that's some good info, and yes the “drag creep” I have noticed with my 10-year-old convectors. Definitely not ideal. With every slight turn or speed increase, current strength. Before you know it the drag is clamped down.
I think I might just go one Tekota and one coldwater. And report back here some results.
Then when my 10-year-old convectors needs replacing I'll know which way to go.
Again thanks everyone, appreciate this community as always. Even though I've been absent of late.
Cheers