I have used many of these, not because they wear out but due to multiple colour changes on one job. You can roll almost up to corners leaving literally a dip of a brush to fill in. They hold much more paint than they look like they should and don't shed, have a couple in oil based undercoat and gloss giving brilliant and super fast results although you will need to lay off with a brush for glass finish. Bearings on the insert too so they don't skid even with really thin paints. Try them out!
Very smooth finish with valspar emulsion paint. Doesn’t work as well with cheapo paint. You need to make sure roller is worked enough to load the paint evenly but not too heavily: not difficult just needs a little practice. No fibre loss.