I too decided to go with the digital Summit box that appears to be made by Mallory ??? not 100% sure though.
I can't comment on durability yet my build is too new. At the time I picked the summit box, I based my decision on 1) Digital circuit on Mallory/summit box) , (my thinking was more reliable??) versus the analog circuit on the MSD box. 2) Cost.
If I ever have to replace the Summit box, I am now leaning toward putting in a Duraspark II Module since my application is for the (475 bhp) street not track.
FORDMUSCLE.com did a comparison back in 2007 using the Mallory 6EZL and MSD 6AL to replace the DURASPARK, check out the link
http://www.fordmuscle.com/archives/2006/12/DuraSpark/
Keeping these boxes cool and protecting them from current/voltage surges makes perfect sense to me.