Regarding the rattle, B&M upstop and guide wheels are spring loaded so the wheels have little, if anything, to do with the rattle you’re hearing. The rattle is likely a roll back, chain dog, or the wheel covers.
Unless a polyurethane wheel is blown out, the wheels have little to do with how smooth the ride is. For example, you can put brand new wheels on an entire train but if the bushings are junk then its useless.