Fair point but it's landside at T4. Even with a following wind, you'll be looking at 15mins from exiting the customs hall in T3 to walking into T4, potentially 30 mins if you just miss a Heathrow Connect.

Perhaps just see how it maps out? If you're going to T4 however the Hilton might be better. I've never been in the Yotel but know the rooms are bijou. Might be a bit too cramped for 4 of you!