My son and I played a 5e game over the weekend. In just over 2 hours with a party of 3 5th level characters (Elf Archer/Bounty Hunter, Dwarf Cleric/Soldier and NPC human thief) he:

Explored a town/interacted with NPCs for leads on a wizard his elf is hunting
Followed trail of the wizard to an abandoned watch tower and found him killed and his lair ransacked by raiders (apparently orcs)
fought the ghoul/servant of the dead wizard (wight with some immobilizing powers) that was guarding his body.
Used speak with dead and found out that the killers included a wizard after knowledge to control magical beasts.
ambushed by 5 orcs outside of a cave, turned into a tough fight as some orcs scored some lucky hits
healed a little, found a secret entrance to orc lair
surprised 3 orcs in lair and quietly dispatched them.
avoided a trap overwatched by 2 orogs
surprised and killed the orogs
found clues to another trap, ignored them, fell in a poison spike pit but luckily avoided getting poisoned (lose 1 HD per failed save per hour then die...that's right...die. It's should have heeded the sign that said "Poisoned pit trap ahead!").
more healing
found orog lair, killed two more orogs,
found 3 goblin slaves and killed them ("they would just lie anyway")
found room with a healing puzzle but missed clues and moved on
discovered lair of a rival wizard behind first wizards murder.
Avoided pit trap that would have dropped a PC into a cave/maze with a minotaur.
Got fireballed
killed the wizard but not before he released the minotaur.
Healed up a bit more (fireball nearly killed the thief and the cleric) before minotauar arrived.
Killed minotaur (too easily?).
Returned to town with some treasure and 2500xp and a feeling of accomplishment.

A complete adventure played out in 2 hours and 10 minutes. I spent maybe 30 minutes creating the adventure and my son thought I had downloaded it somewhere.

Granted, if this was played with 3 or 4 players each controlling one PC it would have taken longer with role-playing and less coordination...but still...3 hours max. This is how D&D should be, although there were a couple times he felt a little too easy.

So afterwards I asked my son (he's 14) what he likes better. 5e with no hesitation. "We get so much more done!". He also likes that traps outside of encounters can still have some consequences. This weekend he has a friend coming over to play some 5e. This kid and his dad occasionally play 1e. He tried 4e and hated it.

So...since 5e is not coming out any time soon and we have two 4e campaigns going with two different groups that are at 6th and 8th do we snag some of that 5e mojo to pick up the pacing of our 4e game.? In other threads I've already gotten a lot of tips for making 4e play faster and there is much to 4e that I very much enjoy. So I don't want to abandon 4e...just want to get it to that point where we can play at a pace similar to what we got with 5e.

So I'm thinking one of our games, we'll do a test run with the following house rules lifted from 5e (with some of my own thrown in)...We'll try it this weekend in the Well of Demons in Thunderspire Labyrinth using RPG Table online...

- Reduce all monster HP by 50%.

- Reduce Monster and PC skills (and init?) by 1/2 level. Change skill training to +3 plus player may improve one skill per 2 levels. So an 8th level PC with a trained skill at 14 (training(5) + 1/2 level(4) + abil mod(5)) would have it be 8 plus maybe 1-4 more depending on his choices of skill improvement.

- Use 5e skill check DC calculations.

-Leave attacks and defenses unchanged (or reduce PC attacks and defenses by 1/2 level and monster attacks and defenses by level? 1/2 level? Seems easier to just leave them so I don't have to modify magic items, feats, etc)

- Action Economy: leave as is

- Charge = Std Action, move 0.5 X speed + basic atk w/ +1 bonus, must be straight line and must move at least 10' (slowed creatures can never charge).

- No action points (deciding to use them slows things down).

-Surprise Round: Move or Action. Surprised creatures don't act on their turns and attacks against them have advantage unless their turn has happened. (so if you go on init 10, attacks on you at init 11+ have advantage)

- Replace surges with hit dice: 4 hp/level = d6 HD/level, 5 hp/level=d8, 6hp/level=d10, etc.

- Expending a HD = die roll plus con modifier (my players will find this more palatable, I think).

- any power that allows/requires a character to expend a surge equals him spending up to half his HD (round up). So healing word on a 5th level fighter,he can spend 0-3 HD. Let's say he spends 2, he gets 2d10+d6 hp back.

- Use adv/dis mechanic for combat advantage and most power/feats/traits/circumstances that give +2/-2 or more (except cover and concealment).

-Saves: use appropriate ability modifier vs appropriate DC (set by spell caster's ability mod or easy, medium, hard DCs for environmental effects), example: Save vs Hypnotism to avoid falling in a fire. Wisdom Save vs 10 + Caster's Int mod.

-Ranged weapon attacks in melee are made with disadvantage

-Spell disruption rules for area and ranged spells cast in melee

-OAs provoked by moving away without shifting (no advantage...).

-Do I need to figure out a way to limit encounter powers?...Maybe they become 2X per day? So a 5th level Rogue can backstab up to 4X per day. A Cleric can Holy Word 4X day? same limit per encounter, though? Don't know...but it has to be simple.

-Dailies are fine I think. I have no strong opinion one way or the other between AEDU/Vancian/Spell points/etc...As long as it is reasonably balanced and doesn't leave a wizard or cleric player (or the DM with NPCs) having to spend inordinate amounts of time choosing things, I'm for it.

Anything else? Bad idea?