Hey,
Thanks to Chris and Sarah's post I tried the Trapaeng Sre / Loc Ninh border crossing today and it all went really well. I left Kratie on a bus at 7.15am and was checked into a guesthouse in Pham Ngu Loa, Saigon, by 2pm.
So I took the bus to Snoul from Kratie that took about 1.5 hrs ($3). Get off at the restuarant / toilet stop in Snoul. The bus driver sorted me out with a motorbike to the border ($4) as soon as I stepped off. Yes, a motorbike with my massive backpack and day back. The driver took my big bag and put in on the floor of the bike in front of him and I jumped on and clung onto him for dear life. Actually he was pretty good so it wasn't a problem. It was about a 30 min drive along a big road that was getting surfaced at intermittend points. There were only bikes and dumper trucks on it, although the latter were mega dusty to pass so thankfully I had a scarf to put over my face.
Got to the border - a wooden hut - and waited around for 10 mins till they stamped me out of Cambodia. Then some random took me on the back of his motorbike (backpack on my back this time) to the Vietnam side - a few hundred metres which was nice to not have to walk. We stopped in at a brick hut, some guy looked at my passport (I don't know why), then said to go to immigration. Vietnam immigration was a massive brand new sparkly building. Only one counter open, but fortunately I just walked up and again another 10 mins to flick through my passport then stamp me into Vietnam. I think all the locals were a bit annoyed they'd just arrived behind the only Westerner for the week / month.
I was told by immigration to take a motorbike for $5 outside the building. Again it was just some random guy so I haggled him down a buck. We drove for 20 mins, this time I felt quite unbalanced with my bag on my back and one on my front preventing me to huddle into the driver for stability. Well I didn't fall off so nothing to moan about really. He took me to a bus for Saigon, which left with me immediately. I had called a travel agency in Vietnam yesterday who told me buses left Loc Nihn every hour. I was asked to pay '5', which I mistook for dollars. I think it should have been 50,000d which is much, much less, but hey I don't really mind for the distance. Something to check in the future. I had to change buses with everyone somewhere in the city outskirts, but after about 3 hours by bus I got to the Mien Dong bus station and then took my last motorbike to the backpacker's area of Saigon - Pham Ngu Lao ($2).
I didn't see any other westerners the whole way. It felt like a total adventure but I was pretty tired when I arrived. I would thoroughly recommend this route as safe (I'm a young female travelling alone), much speedier than going through Phnom Penh and a bit of fun. I didn't feel hassled at all.
Hope that convinces a few more people to take the same route.