I'm a little concerned by the current trends (they haven't changed at all the last couple of days so seem a good indicator) in the latest ladder poll which seem to be generally the removal of many larger maps in favour of smaller maps. Currently there are 14 ladder maps which are true maps with a generally playable area larger than 5x5 (out of 25).
These are:
Badlands
Canis 4v4
Dry Canyon
EOTS
Isis
4 leaf clover
Loki
Melancholy Hill
Open palms
Sera Glaciers
Syrtis
Tag Craft
The Cold place
Twin Rivers
Right now the polls indicate the following will be voted out
Sera Glaciers (20x20)
Isis (10x5)
Syrtis (10x10)
Eots (10x10) or Ambush Pass (5x5)
Badlands (10x10)
The Cold Place (10x7ish)
Melancholy Hill (10x10)
Canis 4v4 (10x10)
And that these will probably come in
Winter Duel (2.5x5)
Moonlight mesa (5x5)
Serenity desert Small (5x5)
Titanus (10x10) or Waters of Isis (10x5)
Williamsons (5x5)
Saltrock (playable 5x5, technically 10x10)
High Noon (5x5)
Perhaps White fire (10x10)
Now I have no objection to people choosing maps, but what I do take exception to is the ladder losing its diversity. I think its fair to say that 5x5 maps leave little room for manouver and hence victory becomes hugely reliant on build orders and spam rather than longer tactical games involving tech progression, multiple fronts etc. I know the reason I bought supcom was to have huge battles and 5x5 doesn't give me that feeling its all too ofter over when you lose one push as the distances are to small, it isn't always, but often it is. A few people I have spoken to in Aeolus share the same sentiment.
Hence I would propose that instead of splitting the maps between GPG and custom (which feels somewhat arbitary) the maps are split by size.
For example in 25 maps it could be good to have 10 5x5, 13 10x10 and 2 20x20 each with a map in/map out vote each season. This in my mind would help preserve the ladders diversity while still allowing people to choose the maps they wish to play.