My 040/25 was drastically quicker than my 030/30 (over double) so I don't think a few extra MHz will make the 030/50 faster than an 040.
Using SysInfo (SysSpeed refused to work with my 030) my 030/30 was averaging 7.2x mips, the 040/25 was 18.xx mips.
Your 030/50 should make it to double figures, but I don't think it'll reach the 18.xx that the 040 does.