I would push the issue. The reason you are installing the East Touch 8 is so you can control the equipment and acessories that you add in the future from this panel, plus if you have to work on pool equipment etc you can shut off the 100 amp breaker and not affect your household items.
Setting it up with a 100 amp service would be the best way to do it and it should not cost 300.00. Wire size should be #2 enclosed in 1 1/4" or 1 1/2" grey pvc pipe and #2 wire is not that hard to work with. If it is a straight run from your box to the Easy touch it should be a piece of cake. Tell the pool builder that you will take care of it youself, sounds like you would be capable of doing this since you upgraded you main panel. The electrician could run the pool equipment etc. wiring out of the easy touch. Maybe the PB and electrician do not know how the Easy Touch works????? and this is why they do not want to use it.
I don't think you will ever overload the 200 amp service, I run shop tools, 2 electric, kilns pool equipment and household loads and never have had a problem, you have to realize all of the electrical items in your house are not running at the same time.
Stand your ground and get it the way you want it. You have to live with it the PB and electrician do not. Just my 2 cents.....