Bear in mind the 400R is just spinning more RPM than the 250/300/350 Verados. Those have peak power @6100 with 6400 max. The 400R has peak power @6700 with 7000 max, so it has to really be screaming to make a difference in regular use.
When I first starting looking for a pontoon I looked at some used ones, they were all 60hp and I would not consider them for that reason. Now I will have that problem if I ever want to upgrade - Unless I can paint that 1 and make it a 4