Hey Charlie,
The jump from 60/46 to 90/60.5 is a bit huge. I refer back to the intent of LL and keep it simple. This should help guide you in your decision. I can, like many before and after me, make it complicated though.
In my 46 year career on the diamond covering 29 states and 4 countries this argument surfaces almost everywhere (players/family's, coaches, umpires, parents, field maintainers, organizers, etc). Decisions have trickled down and up and all around between charters.
From personally coaching this age group (LL, Koufax, CYO and various other organizations) I agree one year of transition would help tremendously. On average, for 13 YO's, it appears running speed, batting reflexes, pitching velocity, infield and outfield arms and the 80/54 yard are a much better fit.
Transitioning is best achieved at the end of your 13 yo year (after playoffs); fall ball is perfect for the jump up. Most leagues are relaxed and laid back and alot of fun can be had on the field.
The obvious drawbacks are limited fields for practice and playing at 54/80 (competing with other organizations) and differing playoff dimensions under current LL rules.
With respect to this topic only: Koufax has it 'dead on'. After 46/60, go to 54/80 (playoffs and national standard) for one year then 60.5/90. Abort changing in mid-season; this messes with everybody and will change the time duration of games; parents care here. Again transitioning in fall ball is very helpful. Then preparing the future 14 YO through winter workouts and private lessons are better defined. Spring turnouts are much better framed by coaches and players.
As a coach this feels right. As a coach the 'realtime' thinking is more respective to the natural tactics of MLB ball as lead-offs, pitching from the stretch, bunting and balks are practiced and refined. THIS IS A FUN YEAR!
As an umpire, for Pete's sake, we should be flexible, open and willing to offer ourselves to the natural growth of youth just like parents, coaches, field maintainers, organizers and all big people doing big things for younger people.
One more surgery and I should be back Charlie!! Miss you all. Al