The x360 is the way to go.
As far as the collection system, I am not sure what model you are talking about. One of the rear baggers or the MC519 cart? All use a powerflow adapter on the deck. Are you complaining about the seal to the deck or the tube that goes to the cart or rear bagger? The tube used to be a two-part, but some models have been upgraded to a one-part tube that is less likely to come apart or clog. Since you mentioned cover, That could be the cover of the rear bagger or the cover for the MC519 cart.
Also, not all dealer service departments are bad. I just got my X304 back from the dealer. I had rebuilt it (had 1555 hours) and stripped the mowing deck and replaced every moving part (should have bought a new deck). It made a horrible noise and was tearing bits of the belt up. I kept buying new parts (was going to buy a new PTO) and eventually the parts department manager took pity and told me to bring it in and let their guys look at it as one hour of diagnostics was cheaper than the parts I was getting ready to buy. Brought it in on a Saturday morning and demonstrated the noise issue to the service manger. He had no clue. On the next Tuesday, I get a call that it was fixed. Cost, $68. The old deck was slightly bent and a blade was just barely hitting the deck when in the normal position. It did not do that when I had the deck flipped over. I mowed with it this last Saturday and it left my lawn looking better than my new X310.