I did a lot of tests concerning HF behavior last night being worried a lot because of Wombat's result.

After all this abxing HF rich 'normal' music I keep up being happy with Helix. Of course this is pure subjective. However I think despite my age I'm not totally insensitive towards HF behavior according to my mp3 listening tests at lower bit rates where lowpassing is a must and where my abx successes have often ben founded on differences in HF. Not a real argument I know.

Anyway there is something specific with Wombat's sample as I have seen in spectrum analysis. HF is cut off way below 18.6 kHz (even without the explicit lowpassing). But I've seen it only with this sample . Spectrum analysis with other samples I've tried was in accordance with explicit lowpassing and did not cut off HF additionally.
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Be cautious when commenting about spectral analysis here.   The HF behaviour of Helix seems very similar to that of Xing (though that shouldn't be surprising).  That is, the > 16 kHz cutoff only occurs during sharp transients, not all the time like in iTunes AAC or Vorbis.
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  file-file MPEG Layer III audio encode v5.1 2005.08.09
 Copyright 1995-2005 RealNetworks, Inc.

 Usage:  mp3enc <input> <output> [options]
          <input> and/or <output> can be "-", which means stdin/stdout.

 Example:
         mp3enc input.wav output.mp3

 Options:
           -Nnsbstereo -Sfilter_select -Aalgor_select
           -C -X -O
           -D -Qquick -Ffreq_limit -Ucpu_select -TXtest1
           -SBTshort_block_threshold -EC
           -h (detailed help)


B[bitrate]Per channel bitrate in kbits per second.
          Encoder will choose if -1. (default)
M[mode]   Select encoding mode: mode-0 stereo=0 mode-1 stereo=1 dual=2 mono=3.
V[vbr_scale]
          Selects vbr encoding and vbr scale.  Valid values are 0-150.
N[nsbstereo]
          Applies to mode-1 stereo mode only.  Number of subbands to
          encode in independent stereo.  Valid values are 4, 8, 12, and 16.
          The encoder limits choices to valid values.  The encoder
          will make a default selection if nsbstereo = -1.
          Valid values for Layer III are 3-32.
S[filter_select]
          Selects input filtering:  no filter = 0,  DC blocking
          filter = 1.
          if filter = -1 the encoder will choose (default)
A[algor_select]  0 = track input, 1=MPEG-1, 2=MPEG-2, xxxxx=sample_rate
C         c0 clear copyright bit, c1 set copyright bit
O         o0=copy, o1=original
X         MPEG compatable Xing header, -X2 with/TOC
U         u0=generic, u2=Pentium III(SSE)
Q         disable_taper, q0 = base, q1 = fast, q-1 = encoder chooses
D         Don't display progress
F         Limits encoded subbands to specified frequency, f24000
HF        high frequency encoding. Allows coding above 16000Hz.
          hf1=(mode-1 granules), hf2=(all granules), -B96 or -V80 need
TX        tx6, test reserved 6 or 8 seems best (startup_adjustNT1B)
            ** v5.0  TEST 1  as of 8/15/00
            ** v5.0  TEST 2  8/18/00
            ** v5.0  TEST 3  default tx6 (prev = tx8)
            ** v5.0  TEST 4  mods to short fnc_sf, ms corr. hf enable > 80
            ** v5.0  TEST 5  fix odd npart, ix clear
            ** v5.0  TEST 6  add reformatted frames
            ** v5.0  TEST 7  drop V4 amod
            ** v5.1  2005.08.09 (see CVS log for details)
SBT[short_block_threshold]
          short_block_threshold default = 700
EC        Display Encoder Setting

Any updates on this?

For music:
-X2 -U2 -V120 - %d

For voice:
-X2 -U2 -M3 -V40 - %d

So how does Helix now compare to LAME?

Regarding the previous post, it seems that there's also a newer version than the one on rarewares... On dBpoweramp codec central there is a Real Audio Helix Encoder Release 6.

So how does Helix now compare to LAME?

This is RealAudio encoder pack that also contains helix.