Surely better to have a good quality Shimano derailleur anyway. I think the Neos derailleurs were/are made by suntour/sunrace which are generally quite low end derailleurs. I understand there may be specific advantages to the Neos design with regard folding bikes but I'd take a higher quality Shimano or Sram unit any day especially the Tiagra shown above. It's rare to see a sunrace derailleur in the UK but if you do it tends to be on budget bikes. Btwin have it on their budget folding bike but a basic Shimano tourney on their higher priced model. I think I also saw one on a toys r us bike. Same as below. It's actually surprisingly hard to find suntour/sunrace derailleurs in the uk despite their shocks and chainsets being common. Whether that is quality related or just consumer resistance is debatable. Visually they don't inspire though.