I built my cube a while ago, but just now getting it to the point where I really feel it's setting into place. I have tried 360 up to 540... 360 felt like I had to make too many good cuts, 540 was too watered down. 400 feels pretty good. From 360 to 400 was mostly multicolored additions (going from 20 total to 40 total), but added 1 of each color and more artifacts as well. Finally, 405 to keep an even pack as well as make a bit more room for further artifact growth.
My ultimate goal is to pimp this thing out with foils and promos. My first mission is to put as many FNM and various foil promo cards in, as many of them are cheap. Next up will be to rid of all the proxies, which can be expensive. Finally, finish off with removing gold bordered and non-pimped cards. I will avoid full-art cards, as they will be reserved for basic lands only.
Banning goes as necessary, but I also wanted to attempt to make each card unique, as well as force colors to stay within their abilities. There are several that are "on the edge" in my cube, but allowed in for now.
Cube Size: 405
405 Breakdown: 270 mono color (54 each), 50 colorless, 50 multicolor, 35 land
Jace, Memory Adept: Too difficult to deal with his heavy milling. Similar to Sword of Body and Mind, but the Sword has several characteristics that make it more balanced, such as a need for a creature and must be able to hit the opponent.
Sol Ring: 2 mana ahead on turn 1 is too devastating. Rarely did a player lose when dropping this within the first 3 turns.
I discourage cards that are near identical with different names. I want to try for a "1-of"... I'd put 2's or more if I wanted more than one copies of anything.
Savanah Lions: Elite Vanguard
Kodama's Reach: Cultivate
Terramorphic Expanse: Evolving Wilds
Fyndhorn Elves: Llanowar Elves
Ravages of War: Armageddon
Burning of Xinye: Wilfire
Arc Lightning: Flames of the Firebrand
Uktabi Orangutan: Viridian Shaman
Cards that are "out of place" for it's colors.
10-18-12 Vraska the Silent > Deathrite Shaman Lotus Petal > Relic of Progenitus
Vraska was a bit underwhelming. Going to try out Deathrite Shaman as I recall it doing well at prerelease and I have heard complaints about lack of graveyard hate in my cube, so he should do well here. Lotus Petal was pretty weak, so further hate and draw come the relic should work out alright.
Been a while... lets see if I can remember all the changes!
Absorb > Supreme Verdict
Grand Arbiter Augustin IV > Detention Sphere
Ulvenwald Tracker > Experiment One
Tezzeret, Agent of Bolas > Duskmantle Seer
Storm Bind > Ghor-Clan Rampager
Slayers' Stronghold > Boros Charm
Duergar Hedge-Mage > Boros Reckoner
A few that were hard to decide, some experimental, etc. But all together, I think it's a good overall changeover.
Just a minor nitpick: Why ban the original card if you can ban the 'copy'? (Savanah Lions, sex monkey, Arc Lightning)
Personally, I love the older cards. I'd rather go all Beta versions of anything applicable! It seems, though, that most people I play with, who are generally newer to the game, prefer newer and/or more recent and familiar cards. I would rather please the masses... I'll still rock the cards, all the same.
So it basically comes down to: Do I keep older versions of like cards or toss in the newer ones? With the 3 you mentioned above, it seems like more people are familiar with Elite Vanguard than Savannah Lions, making a draft selection faster when the card name's are familiar. I, personally, love finding older cards I haven't heard of (EDH was great for that).
Should something come in to the cube that would work better with the "other" card (such as something that makes Cats stronger over Humans for Savannah Lions vs Elite Vanguard), it will be traded out immediately. As it sits, Humans and Elves make more sense, to me, than Cats and Apes.
So there is a few reasons. It matters little to me (unless there is a foil promo in a modern frame of one over the other), but it seems I definitely wanted to keep newer-ish players in mind in the card selection when the choice was presented.
With that topic brought up, I keep debating in my head... Wrath of God & Day of Judgment... They are definitely too similar... just haven't decided which one to replace with what. (Likely, replace Wrath for the same reason Wizards did with DoJ: Let regeneration have a purpose.)
Hit a milestone! Less than 1/4th paper proxied, 1/5th is now foil (with 1/10th being promo!), and a total of over 1/3rd of the cube being real, tournament useable cards. I have also gone to the double-sleeving method using UltraPro Pro-Fits. Finally, I'm building a new, more portable wooden box for this cube. Current one is not very portable, heavy, awkward, etc.