FWIW I have a 450e Husky but it has the bolt for the bar not the tooless 'feature'. When I purchased my saw last year, the dealer had 450e with and without the tooless so I went traditional. My general feeling is that 'less is more' with a lot of these 'features'.
I have found the saw to work well for my needs -- felling smaller trees, bucking, cleaning up, etc. Compared to the old Jonsred I had (something around 70cc), it's got a lot less power, but my back is much, much happier
. The pico chain that it came with is not an aggressive cutter like other standard chains, so one could improve on that by switching the chain.
My understanding is that the e-series also indicates engines with lower emissions and reduced fuel consumption. I realize that many folks still may not think that emissions of their small engines are not that important, but bear in mind that small engines put out much more climate-changing emissions per cc than do automobile and other vehicle emissions. In fact, running a lawn mower for a few hours is equivalent (in terms of emissions) as driving a car for 200 miles! This is due to the lack of catalytic converters and other emission-reducing technologies that are lacking in most small engines -- especially those not sold in CA.