I'll make a comment on the 2 stroke and half crankshaft issues. First, I think 2 strokes have a place, which is mostly where weight is of paramount importance. Hence most line trimmers are still 2 stroke, though US emissions regulations are pushing them out of the market these days. However, those are good 2 strokes. In my opinion Victa made bad 2 strokes, and continued to do so - in fact made them worse - when a number of Japanese mower engine brands had begun selling good or very good 2 strokes. Furthermore I do not see a need for 2 strokes on mowers, where the weight of a suitable 4 stroke engine is usually not a problem. Line trimmers yes, lawnmowers no. Someone will no doubt point out that there is still a special case for mowing steep slopes, where 4 strokes may run into lubrication problems, and I agree with that but I have to add the obvious point that a lot of this steep slope mowing is unduly dangerous and should probably be done with a line trimmer.
On the subject of half crankshafts, even for very small engines such as line trimmers, this is an undesirable technology. Vibration tends to be worse than full cranks, and main bearing life tends to be short. There isn't a weight saving, because the half crank needs to be made extra rigid to keep it from breaking. I regard half crank engines as simply cheap and nasty.
Having said all that, for people who hate mowers and mowing, if you can sell them a half crank Victa cheaply enough they may not care about its inferiority to a full crank Victa. These people sometimes buy 2 strokes because they've found 4 strokes always mysteriously seize up after they haven't put oil in them for a few years.
A long time ago I worked in an engineering department where the engineers reacted badly to this kind of user behaviour. They liked to complain that they didn't design low quality products, they just had low quality customers. That is a recipe for going out of business. The customer is the one thing you can't change, so make it your business to supply something that will work in his or her hands. If you want to not just survive but actually thrive, create a product that real-world customers will enjoy using and be proud to own. If they won't put oil either in the sump or in the fuel, you'd better make them an engine that doesn't consume its oil.
