For the next month, I have decided to use the HP 42s for my daily financial work. I find it better than the wp34s, due to its 2 line screen, and the fact that you can have the menu on screen much more easily than on the wp34s. Basically, it boils down to the same preference of the HP17bII over the faster and more function rich HP30b: user interface wins every time, and solver is key.
The solver in the HP42s is more cumbersome than on the HP17bII: you need to write a program, with a number of standard lines to define the variables being solved; this takes longer than just writing the algebraic expression, like on the HP17bII. The solver on the HP50g is prepared to take formulae from libraries (good for students), but you can define your own formulae and have them used in the solver.
On a more general level, it is a real pleasure to use a pristine example of a Pioneer series calculator. The keyboard is pure bliss to use - one would like to get the telephone book to add, such is the keying pleasure. Then, the fact of having two lines on the screen (sadly missed on most other Pioneer series calculators) helps a lot in knowing where you are (how many times did you key x><y because you did not know what you had in the y register?)
For the coming weeks, I will be carrying the trusty HP15c in my jacket pocket, and the 42s on the portfolio. Let's see which one wins in the long term.
No, it is not for sale.