I have had some issues with flicker in the lamps, but never an issue with lamp life. I do think the fine tuning on the lens shift is lacking on the 8350. I know Epson customer service has been first rate too. To me Sony is an unknown quantity in this area. Your recommendation would have me going for the Sony, but I do wonder if you have a long term track record with these ES projectors enough to confirm the quality.
I don't have extensive use of the Sony projectors. I have run into a few client's who have had them over the years and they certainly tend to be built in similar fashion to other higher-end Sony products, which I consider to be better than most. Still, I have installed an older W5000 projector from BenQ, and it had the worst build quality I've ever seen, yet the W1070 from BenQ is phenomenally reliable.
The client's I've spoken to about their ES models have had good reliability, and nothing about Sony projectors has ever really jumped out to be out of the norm.
This is where Epson differs. It could be in part to their much higher market saturation on lower-end models, but they have reports which Panasonic did not have. So, they had poor cooling, and perhaps slightly higher light output lamps that were blowing up far to often. I also had an issue with their lens shift drifting mechanically because it didn't lock properly in place.
My real experience has been with JVC projectors. You don't hear about color issues with LCoS chips or with build quality issues, or much else. They just are great projectors which keep going and going. The contrast from JVC is well beyond what the Epson or Sony models are hitting with really inky blacks. But, JVC and Sony are different companies. Yet, both put a lot of R&D into developing their LCoS products and really started them at the high end. These aren't products which were cheap from the start. They began expensive, and then dropped in price slowly.
A top down philosophy from top tier companies tends to deliver higher reliability from what I have seen over the years, and that's where the HW40ES fits in. A slightly modified HW55ES, not a 'whole new model'. So, I believe in what Sony is delivering here.
I imagine the better Epson models (5030) are just really rock solid at this point, and much like most of the other models out there, it's hard to go wrong. There are just a ton of really good projectors out there.
But, as I said. I won't use the DI, and I really have liked what I have seen from LCoS over the years. I like that the Sony will be nearly dead silent, and it really does look great.
