Hi Trustytriumph still have same set up but not used for a year. It is a bit of a faff to get the bike on the rack alone...........you really need another person to steady the bike as you're lifting it on. I get my my wife just to stand by the bike to prevent it tipping over whilst I first lift on the the front wheel (this is where you need someone) then move to the back using both hands under the swing arm and lift on the rear wheel, then strap it down. I guess it does flex a bit but I've got the flange tow bar set up so there are 2 bolts holding the bracket instead of it 'sitting' on the tow ball itself. My set up doesn't involve the tow ball.
There has been a question of exceeding the weight limit but my Tow Trust has a nose weight 120kg..........just enough for the Grom. it's never been a problem and I've covered a lot of miles with this set up, I'd probably not fill the tank when carrying the bike..........