Replying to Is 172cm Sir Francis Bacon Too Short?

Everyone in these forums says to size up Sir Francis Bacon skis because they measure short and have rocker.  Based on Line's sizing chart and a conversation with their customer service rep at headquarters (who said they have a long effective edge) I ordered the 2013 model in 172cm (168.2cm actual tape pull).  I'm a 5'8" and 145 pound older advanced/expert but not very aggressive, preferring quick slalom turns in bumps and tight trees at slower speeds rather than charging down bowls. 

When they arrived I noticed that if mounted at the near-center mark they would have as much shovel length as my 164 X-Wing Fury skis (83mm underfoot, no rocker), which I don't find too short except in deeper snow.  I know these could be mounted further back at this year's -60mm "recommended line" (versus the -25mm Eric Pollard line) , but everything I've read suggests that's not a good idea since these were designed to be skied near center.

These would be the only skis I bring on trips out west for use all over the mountain in all conditions, including slick groomers and deep icy bumps in the trees if that's what the day brings (no biggie... I'm from back East).  So the question is, did I make a mistake and buy too short?  Could anyone in my size and weight range who actually has skied the 172cm (not the 178cm) give me some insights as to how they handle in the powder and hardpack?  Also, has anyone skied any length at the -60mm line?

I can't return them for the 178cm, so either I'll just keep them or sell them brand new, unmounted, still in the shrink-wrap for around $550 (close to what I paid).  Thanks for your feedback.