Hello Melb
Well, that's an unusual question.
I think I can only answer one part of it...
I do not believe more contrasted lawn stripes will be achieved by a
heavier roller. There are historic reason why 'heavy-weight' lawnmowers
were the first powered reel mowers.
The 'middle-weight' and 'light-weight' mowers came in to being for a
number of reasons - but their was a clear realisation that good stripes
could be made with very little roller weight. In fact, heavy rollers
are unsuitable for work beyond sporting purposes, and then, only
specific ones - sports fields, cricket, tennis, croquet ...
It may surprise you that golf greens mowers are designed with lighter
rollers; not heavier ones; there being a danger of compaction of the surface
where it is not warranted - or detrimental.
The biggest gain for that 'english striped look' will be found in external
factors: the grass type, soil, height of cut, augmented by regular de-thatching
or scarifying, or other maintenance - and lawnmowing technique.
I'm hoping a lawn expert will help me out here. Your answer lies in turf-
selection and maintenance, not adding concrete. That's best left to the
mafiosi. I think that's right.
Hope this helps.
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Jack