I finally got around to altering my spreadsheet to incorporate all the real damage items. How does blue Ezreal compare to a more traditional ADC build. For reference I swapped out the life steal quints for AD quints and changed the items to berserker's greaves, infinity edge, phantom dancer, blood thirster, last whisper, and frozen mallet.
Do keep in mind that the spreadsheet is an idealized picture of damage done. It's being able to hit all your spells exactly on cooldown, always hit with all of them, and to squeeze in every auto attack. This isn't actually possible. Which build suffers more from this isn't immediately clear to me. Standard ADC likely gets to get in all the autoattacks but should be missing more spells and is more susceptible to being jumped on while blue EZ can kite more which tends to mean hitting most of the spells but missing some autoattacks.
At any rate, blue EZ looks to max out at 992 DPS for 13850 gold, or 7.15 damage per second per 100 gold spent. Standard build EZ looks to max out at 974 DPS for 16300 gold, or 5.98 damage per second per 100 gold spent. Less damage for way more money! You do get a real defensive item in there in the frozen mallet? That's actually probably a worse defensive item than frozen first anyway. Swap those around! With frozen fist instead the standard build gets up to 1066 DPS for 16250 gold or 6.56 damage per second per 100 gold spent. At least now we're getting something out of that extra money. Probably not enough, but something at least.
The last thing I checked was how good the cooldown boots were, and they were way better than the attack speed ones. Maybe that's still true? Turns out it is, barely. The difference isn't nearly as pronounced as it was for full blue build but it's still there.
At any rate, I am now completely convinced. Blue EZ is absolutely the way for me to play when I'm playing Ezreal. It's cheaper, and better, and more fun. Run it!