[texhax] Greek letters relatively too large

[Karl Berry]

    times is obsolete 

I would not call it obsolete.  It works in that it does what it does:

\renewcommand{\sfdefault}{phv}
\renewcommand{\rmdefault}{ptm}
\renewcommand{\ttdefault}{pcr}

If that is what one wants, then it is fine :).  Anyway it should never
go away (or change); that would just cause massive backward
incompatibilities for no good reason.

    and mathptmx and txfonts do the same thing in
    different ways.

I don't think so.  mathptmx uses the ptm* fonts.  txfonts uses the tx*
fonts.  Two different things, although obviously the final result is
commonly all but indistinguishable, visually.

If one is considering txfonts, I suggest considering newtx instead,
which is Michael Sharpe's updated newtx, which has various fixes and
enhancements.  http://ctan.org/pkg/newtx

Michael has also created an analogous newpx and a lot of other
font-update packages.
http://ctan.org/author/sharpe

He wrote an article a couple years discussing available math script fonts:
http://www.tug.org/TUGboat/tb32-2/tb101sharpe.pdf

(Thanks Michael.)

Karl