I also built the DSO150, and did the lipo mod as described in the JYETech forum. I have found it to be very useful. For example, today I was working on an Arduino project which involves reducing the system clock to 1 MHz to save power, while still maintaining a millis-like interrupt every 2ms. I had it toggle a digital pin on each interrupt, and displayed that pin on the scope, including the frequency readout. That showed me it was working properly, but that the correct overflow value for timer0 was 249, not 250.
And the fact that with the mod it's battery-powered means I don't have to worry so much about Dave's video on how not to destroy your scope.
But there are a lot of 150 knockoffs around, and while they work ok, you can't upgrade firmware on them. Banggood is a known good source of genuine stock, at a very reasonable price. They also have cheap "real" scope probe to replace the alligator clip probe that comes with the 150, plus the charger and boost regulator modules for the mod.
However, it must be a year ago now that JYE mentioned in the forum that they were working on a two-channel model of the 150. If that's anywhere near happening, it might be worth wating for, assuming the price is right.