I need some potty training and readiness advice. Please
Background info (sorry if long):

My DS just turned 2 in November, and with another baby on the way I am hoping to get him potty trained sooner rather than later if possible. We started putting him on the potty around 15-18 months and ever since then he's been really good about going whenever you put him on (though not neccessarliy able to tell me when he had to go).We were never very consistent though as we did not want to push the issue before he was ready.

At about 22 months he started telling us (95% of the time) when he needs to poop and we can make it to the potty in time if we hurry. He still doesn't tell me when he has to pee though. I have found though if I take him to the potty every hour his pull up will stay dry all day, even after naps, and often his diaper is dry in the morning. It has been this way for months.

I was giving him a small gummy treat for successful pees and a smartie and a temporary tattoo for successful poops, but now he only gets a treat every few pees (too much sugar otherwise).

I thought maybe pull-ups were holding us back so Friday we went and bought some cute underpants and put them on. He was really excited about his big boy underpants and proudly told everyone at playgroup he was not in diapers but underpants. On one trip to the bathroom he ran into the boys room by mistake and was very interested in the urinals. No one was there so I let him try pee standing and he was thrilled to be able to watch himself pee.

So the first day in underwear we had no accidents, the next 4 days in a row we had one accident per day (all at home, 30 min after his last potty visit) and yesterday we had 2 accidents (one in his bed, and one in the carseat, both close to the hour mark). Last night after his second accident he was crying and when I was redressing him he said he rather wear a diaper (so I obliged).

Today I asked him if he wanted to continue with underwear or go back to diapers and he wasn't sure, and since I have a butt load of laundry to do, I got lazy and put the pull up back on him for today.

I know we have not been trying for very long and I was not expecting instant results or anything, but my question is, do you think he is ready for underwear? Should I persist and keep it up or should I just go back to pull-ups for now? The accidents aren't really a huge deal for me to clean up and stuff, I'm just really unsure of what to do and don't want to push him into something he's really not ready for.

(last piece of info - we started with a small potty but now he uses one of the little seats that sits on the toilet. Would he be better off still using the little one?)