QoS,
I've used a 4' howse medium/light RC (Bush Hog) in both a YM1610D & a YM2010D. Have it on the 2010 D now. The YM1610D had no issue with 4' at all. Plenty of power. Used it some pretty scrubby acreage with some 1/2"- 1.5" live oak saplings. No problem. Occasionally wish I had a 5', but a lot of the areas I shred are very rough, rocky and tight with trees.
The yellow RC's at our TSC are KK, they seem to be on par with Howse, and maybe a little heavier in some ares. Heavy enough for light commercial work if cared for and used with caution.
One thing I would look out for is to check Yanmar's specific RPM designation for your model - it will be on the engine rating plate. I was a little underwhelmed with the 2010 the first few times I used it with the RC, until I discovered that the 2010 "manual" specified an engine RPM that was way off - it spec'd 2200 RPM for 540 in PTO1. Correct is 2500. Don't recall what the 1610 was, but it's on your engine plate. Can't hardly believe anything in the red manual I received; it is in error 75% or more each time a specification is provided. Even contradicts itself page to page.
If you're working commercially, I'd highly recommend the OEM's chain guards, even if they seem expensive. Liability for what collateral damage for a RC can be considerable. If you're insured or bonded, they may require it to assume coverage.