Have had a HX270E for last few years, fairly bullet proof and very cheap, especially now new edition is out. Standard Horizon is excellent about swapping gear for new if any problems, Union Chandlery in Cork has sold tonnes of them and will happily say you couldnt go wrong for the price.
When was looking from memory yep the M33 is more compact, has a smaller battery pack than the M31, this is maybe one of reasons it float, but smaller battery means less battery life??