You want to be working on current-gen hardware if you're baselining future development efforts at 2.x going forward.
What you don't want to be using as your sole dev/test unit is a two year-old device using an unofficial workaround to get an OS version installed that was never intended to be used on it.
It's fine if you want to support those people that decided to use the workaround by having one of these franken-units around as a secondary edge-case device to test on, but it should never be the only device you use to develop and test with. I have a 1Ghz overclocked Sprint Pre at 1.4.5 as my "daily driver" and another Sprint Pre I've upgraded to 2.0 for testing such cases.
Some additional hoops to jump through but it's entirely doable along with overclocking, you end up with a pretty snappy device.
http://www.webos-internals.org/wiki/WebOS_2_Upgrade