I've considered it after many trips.
I've only done it once and probably under the worst circumstances. Three days before I was supposed to fly home, I had been in Provence and wrecked my bike in a solo cycling tour. My flights had been booked roundtrip MCO-LHR-MCO but I lived in JAX. I had spent some time in London and in Paris before going to Avignon to do the tour. On the last day, I wrecked - ended up with a minor wrist fracture, a minor concussion, and a fairly moderate strain in my neck and upper shoulder along with some lovely scrapes on my arms, knee, and face. The plan had been a rest day in Avignon before taking the train to through Paris to London, stay overnight at the Hilton Heathrow T4 then be on my way. Nice, easy, leisurely. Everything went according to plan... except instead of easy and leisurely, I was broken and alone. Made it from Avignon to the Hilton at Heathrow no problems and realised I had booked the wrong dates - and they were sold out that night. Found a quaint hotel not too far away and stayed there. Arrived just in time to get last orders from the restaurant. Airport check-in went even better - someone was looking out for me. I was definitely not a frequent traveller so no reason why this should have happened but someone must have taken a massive amount of pity on me because I was upgraded at no charge. The flight was okay-ish, but turbulence triggered a migraine to go along with the injuries. By the time I landed, I just wanted all the painkillers I could get my hands on. A friend in Orlando picked me up (I left my car at his place rather than pay for parking at the airport). I passed out on his couch for a good two or three hours before driving to Jax. Got really sick around Daytona. Had to find a pharmacy for nausea meds. Made it home. Promptly passed out again. Woke up the next day, went to the doctor, got the good drugs. Stayed home for like a week.
10/10 do not suggest trains, planes, and automobiles in such a scenario especially solo style. If I had been well, it would have been a piece of cake.