Yes, I would say it is better than the 4805. It has a higher resolution, equal contrast, a better 6 segement 5x speed colour wheel as opposed the 4805's 6 segment 4 speed colour wheel so should reduce any risk of rainbows. A point worth keeping in mind though is that it should be ceiling mounted or used on a coffee table, NOT on a rear shelf as it is 12 inches deep and the exhaust( which dissipates the heat) exits out of the rear so needs plenty of space behind it which makes a wall mounted rear shelf a no-no !
The 4805 is fantastic for the money ( I actually own one) but the Toshiba is much more money normally and offers slightly better specs. £1200 for a brand new one is a bargain ! £100 cheaper than the 4805.