It's a mixture. Looking at the current table, from what i can tell:
Ton Pentre - money is the issue, and they would have to fork out a lot of £ to bring Ynys Park up to scratch. They're a strong fish in a competitive pool i guess.
Goytre United - no floodlights. And their manager resigned (and is now at Lido) cos he knew the board didn't want to go up.
Dinas Powys - not sure about them.
Bryntirion Athletic - were in county league football four years ago. Stadium not up to scratch.
Cambrian & Clydach - same story as Bryntirion.
Us - we'll go back up thank you very much
Aberaman Athletic - they've got the dosh in relative abundance. Ground needs a lot of work. They only have 40 seats and have no floodlights.
The Welsh League is bringing in new ground criteria in 2009 which requires floodlights i think. This will help clubs prepare, but unlike in north, ground criteria covers division 1 to 3. The Cymru Alliance is only one division... You could almost say we need a Cymru Alliance South down here to aid with the step up...