Based on experience, a "speed roller" has minimal negative effect on a putting green surface. Cannot recall the exact article but Chris Hartwiger, SE Agronomist with the USGA, came to the conclusion there minimal compaction caused by regular rolling. The only negative effect I have ever seen from rolling a green is on the edges where there is not adequate room to change direction (i.e. bulkheads, bunkers, etc.), some wear can show over time. As for flattening or changing the contours over time, I would expect there would be more change to contours by light and frequent sand topdressing. Finally these machines as I have experienced can be used on severely sloping greens given an experienced operator.