Would either of those work for a round head or will they both kill me?
Dover and other local tack shops are about my only options because I can't have anything shipped.
So if there are any other ASTM certified brands that Dover doesn't carry, but may be at a local tack shop, and are no more than $150, then I would be interested to check those out as well.
It is also important to consider not just the shape of the helmet (oval vs round), but the overall depth. Some helmets don't come down far enough on my head so I can't wear them.
I think you will just have to try whatever is available locally and buy what fits you the best. When it comes to protective headgear, IMO if you have to go a bit above your budget for the perfect helmet it's worth it.
I haven't tried the other two, but I can tell you that the vast majority of helmets are made for OVAL heads, not round. I have a bowling ball for a head - very round, and most helments pinch me in the temples, but have too much room fore and aft. The skull I have, that fits me like it was made for me, is this one: http://www.doversaddlery.com/charles...5ukl55l2ou3qe0. I know it's a tad more than you wanted to spend, but I think the extra cost is worth it for comfort.
My regular schooling/show helmet for dressage/stadium is this one: http://www.doversaddlery.com/irh%c2%...5ukl55l2ou3qe0. It's not completely round, but when i tuck my ponytail up into it, it fits pretty well and is very comfortable. The other model of the International helmets that look like this (but less expensive) are more oval and don't fit me at all.
This one also fits a round head (I also own this one - I've been in search of the perfect helmet for a looooong time):http://www.smartpakequine.com/irh-at...x?cm_vc=Search. It looks like the oh-so-fashionable COs, but those don't fit round heads, and this one does.
"Opportunity is missed by most people because it is dressed in overalls and looks like work." - Thomas Edison
So, the Zen Buddhist says to the hotdog vendor, "Make me one with everything."
I went up to Dover today and tried them all on... ended up getting the Pro II. It was just a little tighter on the sides than the J3, but I really liked the vents in front since I live in GA. Now I just need to work on a Sipps cover