The Stock antenna is not bad for me. I replaced it with a Diamond SRHF40 and Diamond SRH789. The SRHF40 is nice. I like how bendable it is. I drop it in to my pocket and don’t think about breaking anything. The SRH789 I bought for going out of band. I don’t use it as much as I thought I would. I have been using it in addition to a long wire for listening to SW. Now you can get a quad band SRH-999. This would be nice at times, but it is large and I would be concerned about breaking my SMA connector. Additionally, I am now using a mag mounted tri-band antenna for use in the car.
About the time I am willing to sign the praises of the GPS with APRS I get some wild * reading or no readings at all. According to the online maps, I was several miles out to sea the other day (I was not out in the ocean.). I was unable to get decent readings in DC around the whitehouse, capital building, monument row and such. The GPS would not sync up to the satellites as I drove down the road. Then the next day it is accurate enough for me to walk to the exact spot I was the day before.
As far as GPS on the MIC or on the radio, I think that is very subjective. If you want a wired mic then it has to go on the mic. If you don't then it is going on the radio.
Battery life is an issue. With GPS, APRS, listening on the other channel, TXing very little you will not get 8 hours out of the standard battery. The AA conversion pack is less than useful, because you can not get 5W output. The larger battery is pretty good. It will last me a full day.
I would also suggest you get the cradle charger. I didn’t for the first couple months, but I can see that the charge port cover is not going to stay water tight if I keep plugging it in every night.