If I were you I would sell your existing scope and buy either an 8” or 10” Stella Lyra dobsonian. They are better finished than the Skywatcher and comes with some great extras like a dual speed focuser, an 8x50 RACI, and cooling fan. I owned the 8” model before upgrading to the 12”. 4” doesn’t seem a lot but in the flesh the increase in size is very substantial. I use a sack barrow to wheel it to my observing site and it can be a struggle to mount it onto my EQ platform. I would try and see a 12” with your own eyes before making the commitment. Flocking can make a small increase in contrast but it’s nothing significant.