If you want to eventually go full time and there are 22.4 positions available now I would bid into 22.4. Doesn't pay progression reset because you are going from a part time position to a full time (unless of course you are already making more)?
Going to full time you can start building seniority to bid into an rpcd position sooner (unless that changes) and seniority for bidding a route. Company seniority only applies for vacations, so ANY 22.4 that gets in before you go to full time will have more seniority than you for bidding routes.
All of what you said is very true and all points that I have considered. My reasoning behind starting in Utility and then later on bidding for 22.4 (whenever they post bids for it again) is:
1) Once I make my 30 days as utility I get red circled in at @~$33 an hour, and keep that if/when I go 22.4 rather than the lousy $20 they start at
2) If I understand the wording in the contract correctly: once I work 60 days as a cover driver, I will then automatically qualify for any FT driving i.e. there's no silly 30 day qualifying period for joining 22.4
3) If I ever decide to switch buildings and do 22.4 to another nearby one I will have the option to do so
You're right about seniority though, that's the only sucky part. But I'm hoping they'll post bids for 22.4 again once I'm done with my days as Utility.