Track performance is not always a good indication of autocross performance- GT-R is a prime example of that. On top of that, you can't take snapshots from Laguna Seca without comparing track conditions, driver skill, etc. If you look at Nurburgring times (fairly well documented on wikipedia), the fastest Boxster S is a full 30 seconds off the faster GT-3 non-RS, and even further from the RS, and there's a good chance it was track-prepped. Most Boxster/Caymans fell more in-line with the S2000 and C5 Corvette.
I'm going to snapshot one Boxster right now. Which class does it look like it would best fall in amongst the other class-topping Porsches here?
CANDIDATE A: 2978 lbs, 310hp/266ft-lbs
SCCA SS: 3131 lbs, 408hp/310ft-lbs (2011 997S)
SCCA AS: 2910 lbs, 300hp/258ft-lbs (2001 996)
SCCA BS: 2911 lbs, 258hp/229ft-lbs (2004 986S)
Candidate A happens to be a 2011 Boxster S, presently classed in SS, despite having virtually identical power:weight with an AS 996. For SEB to justify classing it in SS, there would have to be rationale that the 987.2 to be too fast for AS due to other factors. I'm pretty sure it's not the tires, as 987.2 is running the same width wheels as was optional for the BS 986S in 2004 (7.5x18/9x18) and is a little heavier than the 986S to boot. PDK has not proven to be the advantage it was expected to be when these cars were first classed, nor has mechanical LSD shown itself to have a measurable advantage over the electronic LSD offered in earlier Boxsters. I'm trying to find a link with skidpad data someone linked me to a few months ago, but as I recall, the Boxster/S did not do as well as the 911 (and especially GT3) despite the weight distribution, due largely to items we cannot change in stock class. The sole advantage the 997.2S Boxster has over the 996 it has is lower polar moment of inertia.
Additionally, I think the fact that nobody has fully developed a 987/987S for SCCA stock class really shows that the community at large feels they're not classed properly, and anyone willing to take the time/money to max it out has gone to other platforms or taken it to street prepared, etc.
In summation, I still feel pretty strongly 987s should all be AS/BS vice SS/AS. With SS one of the largest classes at nats and so many S2000s leaving for STR, I think it makes a lot of sense balance-wise, too, even if the 987 is deemed to be on the seam between these classes.
Wall of numbers:
Nurburgring Nordschleife lap times:
7:24.22 Nissan GT-R
7:29.03 Nissan GT-R (Stock GT-R on stock tires)
7:33 Porsche 911 GT3 RS 997MkII
7:38 Nissan GT-R (On Dunlop SP Sport 600 run-flats)
7:42 Porsche 911 GT3 (2006)
7:42.99 Chevrolet Corvette C6 Z06 (2005)
7:56 Chevrolet Corvette C5 Z06
7:59 Chevrolet Corvette C6 Z51
7:59 Porsche 911 Carrera S
7:59 Dodge Viper SRT-10
8:10 Porsche Boxster S
8:12 BMW Z4 M Coupe
8:13 BMW M5 E60
8:16 Porsche Cayman S
8:17 Porsche Boxster S
8:25 Porsche Cayman S
8:28 Porsche 911 Carrera (993)
8:32 Porsche Boxster S
8:39 Honda S2000
8:40 Chevrolet Corvette C5
SCCA SS, 2012:
2010-11 Porsche GT3: 3075 lbs, 435hp/317ft-lbs
2011 Carerra GTS: 3131 lbs, 408hp/310ft-lbs
2009-11 Carrera S: 3131 lbs, 408hp/310ft-lbs
2009-11 Boxster S: 2978 lbs, 310hp/266ft-lbs
2009-11 Cayman S: 2976lbs, 320hp/273ft-lbs
2009-11 Boxster Spyder: 2811 lbs, 320hp/273ft-lbs
SCCA AS, 2012:
2003-04 Carrera: 2959 lbs, 315hp/273ft-lbs
2001-02 Carrera: 2910 lbs, 300hp/258ft-lbs
2009-11 Boxster: 2942 lbs, 255hp/214ft-lbs
2009-11 Cayman: 2932lbs, 265hp/221ft-lbs
2007-08 Boxster S: 2987 lbs, 295hp/251ft-lbs
2005-06 Boxster S: 2965 lbs, 280hp/236 ft-lbs
2007-08 Cayman S: 2976 lbs, 295hp/251ft-lbs
2008 Boxster RS60: 2987 lbs, 303hp/251ft-lbs
SCCA BS, 2012:
2007-08 Boxster: 2887 lbs, 245hp/201ft-lbs
2007-08 Cayman: 2866 lbs, 245hp/201ft-lbs
2005-06 Boxster: 2855 lbs, 240hp/199ft-lbs
2003-04 Boxster S: 2911 lbs, 258hp/229ft-lbs
SCCA CS, 2012:
2003-04 Boxster: 2811 lbs, 228hp/192ft-lbs