Calbs,
I demo'd the 8'10x30.5 mana and the 10'x32 mana on the same day last week.
They are
completely different boards, with the 8'10 mana being a lot more performance orientated than I expected, more pulled in nose and way more fun on a wave. Stability when just standing, and paddling to break seemed not much difference to the 10' for me at 80kgs. However, My friend 100kgs who owns the 10' mana really struggled and didn't bother. But I got fatigued sooner and had to resort to my knees going out, have to take waves a lot later than id prefer and fell more than id like, especially in chop. This is normal of course for shorter boards. Im sure id improve with this as would you. But something didnt feel 100%. Its harder than the simpler fanatic 8x10 allwave which is instant fun and perhaps good if your coming from 10' mana. a bit corky for me though. Your needs and skills will be different to mine, as how big a jump you want to make.
To me, your current 10'x32 Mana has too much rocker, too wide, too much volume up front and fat rails and lacks longboard feel that other similar size boards have. Just changing shape rather than going too short will really make a difference. You need to decide if you want longboard feel or shortboard. Im thinking coming from mana 10' - 8'10 performance shortboard might be too big a transition? a softer approach might be if not allwave, perhaps starboard WP, converse, or if your after more shortboard style - hokua 9.5, fanatic prowave 9'3 and JP 9.2 (which felt more stable than 8'10 mana but not decent waves to truly test feel). so im as confused as you and have a 8'10-9'6 thread going which may help..