I have been looking at some on Ebay, they don't point down so much,giving 2" rise at the end of grip,,dunno really
Looking at woodcraft riser ones personally not cheap but good quality, need to look at bike and work out how much the oem are raised and then buy accordingly, as only want about half inch more raise than oem fitment
Just bought some Harris ones which seem quite nice, haven't fitted them yet so not sure how much rise they'll give, if any but have got adjustment in other ways
Going back to your first question, cheaper to replace if you do have an accident as you'll on need to replace the tube and not whole assembly and tubes are about £25 for the pair compared to £122 roughly per side for oem Fitting wise you can just take off the top yoke and fit that way I believe