Well, yes and no. We are currently having our upstairs shower room and lav renovated. The pipework for the macerator lav was copper, not plastic, which is bad; and had lots of elbow joints also bad; and went to exit pipes that were narrow, bad, bad, bad. So the underlying pipework might be a bit, er, shit, and so you may or may not solve the problem of a toilet that seems to block too readily just by replacing the toilet. How far has your plumber/bathroom fitter investigated?