I would like to just post my review of the PSP-290 and the Holux GPSlim236. I have used both of these with the latest versions of MapThis. Please note i was using in a suburban area about 10 miles north of Detroit.
PSP-290
I used this with many different prx combos. I ended with the 2.71 3.03 combo on firmware 3.03OE-C at 111mhz.
While out side in optimal conditions i would get a fix in about 3 minutes. While in my car not moving it would take any where from 3-5 and that was if i even got a fix. signal strength would never be above 2 bars. I would often be shown about 20 feet away from my actual location. by this i meen instead of being on the road i was driving through houses. i assume this si from lack of signal strength. If i was lucky enough to get a signal and it were to drop from going under a bridge i most likely could not get another fix. All around it was pretty lousy. The only pros are no wires and it is small and shiny.
Hloux GPSlim236
Used my own DIY cable that was very easy to make useing a 1k resistor. Takes less then 40 seconds to fix in my house in my room which is dead center of my house. While outside it seems to fix just as fast. While moving in a car it can take a minute or more. Also it can be slow to get a full signal while moving. Usually a good stop at a red light is enough time for it to get full signal. Very accurate on location. only a slight lag in positioning. When i pass a street it is about 2 seconds behind. If signal drops under a bridge it reconnects very quickly. Battery last for about 8-10 hours or so. Charges quickly. The only con is if you are running around and constantly shutting on and off the unit, it will tend to lock up and not fix. I don't know if it is just my unit or all. It seems that you can turn it off then back on 1 time before this happens. if it does i had to let it sit for about 2 hours before it worked again.
All in all the psp-290 is just shiny plastic and unless you live out in the country i would not recommend it. You can get a GPSlim236/240 for $60/$80 respectively. I understand making the cable can be the #1 deterant from this unit but I plan on making a detailed pictured guide on making a cable. I hope this helps some of you make a decision on which to get. Also i plan on putting a cable auction up on ebay. that moby site seems pretty shady. although i hear everyon gets there cable i think more people would feel more secure being protected by ebay. my seller name is jpc1284 for keep a lookout for it.