I haven't played the Beta, but judging from what you guys are discussing I would have to agree if the mines are big as cruisers or capital ships I would have to say thats too big. A mine is a nothing but a pure explosive. If a Mine is the size of a capital or a cruiser, it would completly destroy whatever it hits I would think, unless they loaded it with salt -peter heheh. Second if they were that big it wouldn't be as believable that it requires scouts to see them. Example:
Capital ship has a large number of crew, unless they are blind, somebody is bound to see a huge floating explosive in space.
"Look captain a huge Mine!!!" (Points out window at large capital ship sized object)
*Capital Ship ship captain* "Don't worry I'm sure its nothing, just watch out for enemy ships"
"But captain is says 'Danger! Mine!' on the side!"
*Capital Ship Captain* "Like I said nothing to worry about, Just ram through it"
"But -" KABOOOOOOM!!!!!!
If they are smaller like trade frigate sized or less i could see how they would be missed in the heat of battle, and scouts would have the designated task of finding mines. Sort of like how carriers have the designated task of carrying fighters, and support frigates have the job of repairing or supporting freindlies. But these are just my opinions.
If however they are actually smaller than a trade frigate, as it was said they were zoomed in, then I believe they are the right size.