My sister has just come back from MCO and flew your planned trip here is what she thought.
No1, Yes there are less screaming brats and the cabin was indeed a bit quieter, the people in the cabin seemed to understand the reason of premium travel and was not much noise.
No2, look at the Virgin web site, only the LHR planes have the NEW Premium seat, my sister said that the seats
looked tired but comfortable.
No3, meal service was good and food had good flavours.
No4, She felt that the crew, all female, spent too much time talking among themselves, seem to lack experience/polish.
Would she do it again? NO. She voted to upgrade on the night flight back to UK but Y on the outbound.
Hope that helps you.
you don't get a second chance to make a first impression!