Impressive. I remember when the opening schedule came out and it was something like eight round-trips per day.
As to the Airport vs North bit, there are two reasons:
(1) Service to DeLand has been slowed down due to low ridership estimates (something like 750 pax/day) making it a poor choice for federal funding. I like the idea of that expansion, but it simply becomes a lower priority at that point. It also doesn't really connect to anything significant (save perhaps the Silvers).
(2) On the other hand, a connection to the airport would probably be a big boon on several fronts, not least because of the probable Brightline connection there (with a rising chance of a connection to both South Florida and Tampa in time).
Mentioning southern extensions, btw, I stumbled across this report today:
http://polktpo.com/docs/librariesprovider2/tpo/sunrail-feasibility-study.pdf?sfvrsn=4
Reading the report, I sort-of agree with Polk County that the extension wouldn't make a lot of sense...but if Brightline weren't in the picture, I would
really like to see what the numbers would look like if they examined an extension to Tampa (Lakeland, in particular, connects more logically to Tampa than to Orlando).