Oh God, I hope not. Missing just one episodes from DVD Release (even if it is filler) would be terrible. Having it on Collection 8, won't be as terrible since I am double dipping and getting the Collections as well, but it would be bad for the people who aren't double dipping. I am going with Season 4 - First Voyage being Episodes 206-219 as well since it will cover that last filler episode as well as all the Davy Back arc.
The series did broadcast in HD from episode 207, however the DVD most likely won't be HD at this point until episode 229 where the Japanese DVDs started to release in HD. I don't believe FUNimation will get the masters to the HD footage at 207, so if they decide to release the first season 4 DVD at episodes 206-219, it shouldn't look out of place.
You're confusing HD with Widescreen. DVDs cannot be HD, period.