Anyone got one of the new style HB511 trailers? good or bad reviews? any issues what with them being a new model? do you prefer the old 510s? we had a nose round a new 511 and were most impressed (and i'm accutely aware i start a PAID job in august so it's top of the "must buy" list), but with them being a new model, was curious as to whether anyone was having any issues with them before setting my heart on one!