When I had a look at the SupaSwift Big Bob Today N1KK0 , it was just the front section on the base that doesn't have that sort
of swage line to strengthen the sheet metal .
FWIW I think while the profile of the deck may look similar to the Big Bob/Supaswift one - I don't think they're the same - I recall before I purchased the HUT216 I was in checking out the current range of Supaswift Big Bobs, as they'd had an excellent reputation as a well powered 21" utility mower.
The owner of the business talked me off them saying he was very underwhelmed by the cost cutting in their range and had a spare part deck to demonstrate this - the steel was laughably thin and flimsy with a very cheap and nasty paint coat.
It wouldn't surprise me if SupaSwift has cheapened the base now but the old SupaSwift mowers I've had have been good.
I looked at both the SS and Honda side by side online (see Below) ,the Honda looks like they use better wheels than SS .
The Honda Wheels look exactly the same as Pope Wheels and that's what I fit to my SS mowers if I need a
wheel replaced.
There are a few too many SS mowers here so if you put some pics up N1KK0 of your Honda 21 ,I can add some SS 21 pics
to compare the base if you like.
Cheers
Max.