candoo
What a load of rubbish. As a travel agent I can say that that there is absolutely no difference - from the Pre-Reserved Seat aspect - whether you have an e-ticket or a paper one. The only difference between the two documents is in the way that the 'ticketing line' is entered.
The only other comment that I would make is with regards to sameday return checkin on British Airways. If you have checked in for your return flight and then want to make a change, it is impossible for your travel agent to revalidate your ticket without having to telephone British Airways. To do that the agent will be charged the sum of 50p per minute whilst on the telephone - more than the miniscule commission that the airline pays. If you are likely to want to change your return flight time then I suggest that you do not checkin - then call your agent and they will have changed your reservation and revalidated the coupon within a couple of minutes, and wih no inconvenience to yourself.
On the subject of e-ticket versus paper, I would go for e-ticket every time. It amazing how many times I get calls from an airline checkin desk to say that they have apassenger with them who has lost their ticket, and who do not want to have to pay for a Form of Indemnity to be issued. Equally amazing is the number of times that the ticket suddenly appears after you tell the passenger that it is the airlines charge and must be paid!