They will work for some, but not for everybody.
MaP testing for the Wellworth models is:
Elongated bowl, 125 grams
Regular bowl, 250 grams
When MaP did their testing, the toilets tested ranged from 125 to 1100 grams.
MaP thinks that 250 is the minimum that should be used.
If you have the regular bowl Wellworth, you're right at the low range of performance, which is all some people need.