I have two sets of flat thai pads. One cheapy pair that are good quality that a friend gave me. They have taken a beating for a couple years since they were donated to my gym. The other set i have are Warrior Thai pads that still need more breaking in...ouch...lol. Any way, what is pro-con when it comes to curves vs flat thai pads?
Largely personal choice. I prefer flat, both to hit and to hold. I particularly don't like holding curved pads for teeps or knees (bottom pad pointing down, top pad facing out) because they don't lie flat against one another and as a result it feels less secure.
I have been investing in pads recently because i intend to expand my little training group. I bought a Twins belly pad that lends to pretty good coverage for teeps when i use my thai pads as well. But i see what you mean. Without a belly protector the curved pads would seem to lack coverage for knees and teeps.