Martin,
AFAIK - the AOPA course is structured to give you so many hours of aeros instruction and during that time you will be demonstrated and then expected to fly the aerobatic building blocks, loops, rolls, stall turns, spins. All aerobatic maneouvers are composed of one or more of these.
At the end of the course you receive an AOPA certificate.
A standard aeros course is just the same as the above but you choose how many hours you want to fly for, once you are competent with the building blocks you have a greater say in which maneouvers you want to fly. You don't get an AOPA certificate. I tend to take aerobatic instruction each year to widen my reportoire and to make sure that I'm not doing anything unsafe.
So I guess that you take your choice!!
There is a vast difference between Sunday afternoon "drilling holes in the sky" and the rigourousness of competition aerobatics. Comp aeros are judged very much like figure skating or dressage - one starts each maneouver with a perfect 10 and each 5 degrees off heading (or vertical, horizontal, 45 up or down, erect or inverted) costs you half a point. A typical sequence has something between 9 and 12 maneouvers once you are no longer a "beginner". Beginners are expected to fly 4 or 5 but all categories are expected to complete the sequence in a square kikometre of airspace. The bottom of the box is 1500' for beginners and 1000' for the next two higher categories, after this at Advanced it comes down to 660'.
MadGirl's aileron rolls and barell rolls DO NOT feature in competition flying. Axial (slow) rolls - which can be really fast - circa: 400degrees/sec with the right machine and flick rolls do feature, though.
It gets worse.... you are expected not only to fly the maneouvers in the correct sequence, you are penalised if you "insert" a maneouver and you receive zero if a maneouver is flown incorrectly or in the wrong direction. So if you fly a half Cuban (S&L, 5/8ths of a loop, inverted down 45, half roll, erect down 45) rather than a half reverse Cuban (up 45, half roll to inverted, 5/8ths ofa loop to S&L) you'll get zero, zip, nada!
If the sequence calls for you to do a vertical half roll on the way up a stall turn and a 1/4 roll on the way down, you'd better be bloody sure which way you need to roll on the down line or you will be 180 degrees out AND everything afterwards will receive a zero. Ie: instead of recovering from the stall turn downwind or away from the judging line, you recover upwind or towards the judges if cross box you have just forfeited your chances of scoring well.
Is it worth it? Oh yes, great fun, improves one's accuracy and a/c handling an awful lot and there are a fun bunch of girls and boys competing currently.
I don't have an AOPA certificate but I do have a bronze medal won at an International comp - and I'm bloody proud of it!
Stik