I don't think bulb life is a big factor in going with a 90" Sharp. For example, the Sony LMPH202 replacement bulb for the HW30ES, HW50ES and VW95ES can easily be had for $300 and I would guess should easily last you a year (depending on your viewing habits). If cost is your primary concern (which I guess it is since you mention bulb life), I suggest you work out the all-in cost based on your own viewing habits.
The best reason to go with the Sharp is that you can watch it with the lights on and window shades up. However, if you can control the light in your room a projector set-up can probably be had for less, even accounting for replacing bulbs over the life of the projector.
You may also prefer the look of a projected image over that of a direct view LED panel. Personally, I do. Just like I prefer the look of a plasma display over that of an LED display.