typical Allegro learning curve ?

 I would go with Mentor Expedition if it's a choice.  Allegro is a lot harder to use especially if you use Concept as the front end and under Unix (you are talking about months!).  We have been using it for about a month now and still struggling.  To me, Mentor has easier user interface, better support and they usually respond to your questions within 30 minutes.  However, Mentor is very buggy and you need to keep updating the patches.  The auto router is not as good.

When I train an "expert" level person hands-on with Allegro it takes only a couple of days to become proficient enough to generate final output because that person knows what *should* happen and just needs to "map" it in their brain to Allegro.  Unfortunately without a knowledgable guide even the most saavy designer can get lost quickly in Allegro.  The training that comes with the tool is typically not enough to "train" someone.

That said, becoming expert in Allegro is just a matter of time and personal drive.  A 15+ year guy should be very capable in under a month if they are on the tool 30+ hours a week.

A newbie can take 3-6 months to become proficient at the entire PCB design life-cycle if they have no concept of stackups, footprints, routing strategies, post-processing.  That again is with constant mentorship.

Perhaps a strategy is to match your layout team with one of us gurus (me or any number of folks on here) and hold their hand for a few days on live screensharing and then propagate that knowledge forward into your team?

I know Cadence offers training as well so you might check with them to see what they can offer.

Have your salesperson show you how Expedition does adjacent layer parallelism DRCs.

(recovering Mentor user here.) 

 Does that imply "good" or "bad"?  Never used Mentor so I am curious as to how it compares....

We used to have a team of 3 people who evaluate the PCB packages on the market.  We tried Mentor Expedition,OrCAD-Allegro, Concept-Allegro, OrCAD-OrCAD, PADS.  As far as I remember, we gave Mentor Expedition a 10 (not to be perfect, just to normalize so we can compare) and OrCAD-Allegro a 9.

Mentor is a easier to use and a lot faster to create footprints in the library.  The push/hug/shove functions are much better than PCB Editor (at least for v16.2). 

I think Allegro/PCB Editor can be a lot better if they have the default values/functions.  For example, if you want to generate artwork, with a single click,  you can generate the gerber files with default settings without having to turn-on/off the colors. These advanced features should be in the advanced tab.  The color thing is another example.  Why the default colors are almost all gray-green?  Why not make some default schemes? Of course users can select their preferred colors, but the default colors are just too confusing for new learners and too dumb for experienced users.

PCB Editor has some new functions that were in Mentor for years.  Like the way you create footprints (wizard) and mirror/flip view of the board (16.3).

Allegro/PCB Editor has something that Mentor does not.  The Cadence spectra router is smarter than Mentor's auto router. Allegro does not crash as often.  Allegro does not release patch everyweek to fix hundreds of problems (don't know if it's good or bad).  Allegro use more common names than Mentor (they call a footprint as a cell, a symbol as a component...).  Allegro files are very easy to manage.  A brd file is all you need for a board.  For Mentor, you need a whole directory of files, if you manage manually.

However, I have to admit that both Mentor and Allegro are very capable, if you know the tricks.

Finally, the support is the last straw.  Mentor has better support.  We have never waited for more than 30 minutes to get the response from them (although we were frequently referred to as the bug of the software and had to install new patches to fix the problem).  I don't remember hearing that "all of our support engineers are currently assisting other customer..." thing from Mentor.  For Cadence, I don't remember NOT hearing it.