I also expect more multicolored decks. You will want to run all 5 Moxen in your deck almost no matter what.
I was leaning the other way, since splashing with basic lands (which is essentially the fixing power of Moxen) is quite bad. Bear with me, obviously you run all five Moxen, and you run them instead of lands (unlike, say,
Mox Diamond, which counts as a spell). That means you have 11-12 lands left. Using just basics, you could achieve a 7/7 split in a two color deck at best (since you run three off color Moxen), which is quite atrocious, especially if you're trying to cast double pip cards (e.g.
Counterspell and
Eternal Witness). Part of your Moxen will surely act as
Wastes that don't count as your land drop for the turn.
Hence, I expect having five Moxen in your pool would have the following effects on deck composition in respect to colors.
- Dual lands are (even) higher picks in this format than in regular cubes.
- Color intensive cards (like Bloodghast and Necropotence) are harder to support in multicolor decks.
- It's easier to play a "monocolor" deck that splashes for one or two other colors than it is to play true two or three color decks.
I agree with Velrun that aggro becomes a lot harder to support. Basically you're skipping ahead one or two turns on average in mana development each game, which gives aggro decks 1 or 2 turns less to capitalize on their early threats. The only type of aggro that stands a chance in this environment, I feel, is a heavily disruptive style like Death & Taxes in Legacy.
Here's an interesting article to maybe point you in the right direction, though I expect a player of you caliber will already have realized this
