My friend has used Exodus on at least 5 occasions and like Dorian has gone back to them time after time. So that speaks for itself.
I first did the Everest base camp trek with a company called Travel bag 10 years ago. They were cheaper than Exodus by several hundred pounds, but they were excellent. Like all of them, they used a local trekking company. Mine was called Ammadablam tours? Or something along those lines. Interestingly enough, I did see the Exodus company doing the same trek. The only difference I saw was the company Exodus was using had one English guide. Where as we had all Nepalese.
I understand how both Dave and John feel and I agree it is much more rewarding to do the treks on your own. Since the Everest trek, I have trekked independantly in Nepal ever since.
However, I think it all depends on time and money. And what Phil values the most. If time is short and money not an issue, then the trekking company in the UK probably is the best bet.
One thing I would say Phil, is book the flight on your own in the UK. I think the new Indian company JET AIRWAYS will probably do the cheapest flights to Katmandu. Check out there Website for dates. I think they will be hard to beat. And they are a superb Airline apparently. I`m flying with them next week.
Enjoy the trek, you will love it I`m sure.
By the way Dave...nice to hear you mention Gorakpor. However, that overland journey is pretty hard work by any ones standard. I have had to do it several times and it hasn`t got any easier. But it is certainly the cheapest and fun way. Though I`m not sure that I would recommend it.