Overall, I have had a positive experience using Captain Al'Rahem in my Tallarn 23rd Regiment.
I don't always take him, but I do take him about half the time. My army is Tallarn after all.
Here are some thoughts on my uses of Al'Rahem.
I usually tool his platoon out with a flamer or two, 4-5 meltaguns, a pair of voxes, meltabombs, and power swords and I either take a 26-trooper blob with commie or a 36-trooper blob with commie. If I can spare the points it is also nice to toss in Priestess Badra and her eviscerator. Yes, that gets expensive and runs 320-460 points. Plus, add in 30 points for the CCS' astropath--this advisor really makes the Al'Rahem gambit less of a gambit and more of a tactice. However, you're talking an awful high points cost for points that could often be spent in nifty things like tanks, vendettas, meltavets, and platoons of PBI. Thus, I really only take him in games of 2,000 points or more.
Note that in a 2000-point hybrid list I often run Al'Rahem as a 26-trooper 5 meltagun-platoon and support him with:
-3 vanilla LRBTs
-2x36-trooper LC-plas platoons (one of which is fully mechanized into chimeras) and in which one of the PCS' is kitted out with meltaguns and meltabombs
- A vendetta for this PCS squad to ride in
-a LC/vox/standard CCS (Captain Assad or Captain Khomeini commanding)
Since the new IG Codex came out May of 2009 I have learned there are two ways to use Al'Rahem and his blob:
1.) The wrong way--outflank him in onto a flank unsupported by anything else in your army. If deployed alone, Al'Rahem and platoon will usually kill something and then die horribly.
2.) The right way--either outflank him in onto a flank that is adjacent to my gun line or move him in somewhere else far away from my gunline with 1 or 2 supporting flanking units such as stormies, scout sentinels, or vendetta/valks with meltavet squads or, in this case, PCS meltagun squads. I have also supported him with a meltagun blob platoon which deploys in my DZ and then uses "Move! Move! Move" to run across the board and link up with Al'Rahem's platoon on the other side of the board by turn 3 or 4. If deployed in tandem with other units, for some reason, Al'Rahem's lethality reaches a sort of critical mass that allows him and/or his blob to survive to contest enemy objectives and cause mayhem. Well, come to think of it, usually just his blob survives because a squad of 5 IG troopers with 3 or 4 meltaguns, a nifty sword, and a plasma pistol just hanging out in an enemy DZ for some reason has a low life expectancy.
His orders ability (especially Bring it Down! and Move Like the Wind!) also grant me fun and potentially effective tactical options. Although, for some reason, he is better at successfully screaming BiD! than any other order. This is not a bad thing.
Note that in 40K plans often go "awry," as the vox man said. While the ability to deliver special weapons shots and infantry blobs onto enemy DZs (usually on Turn 2) is good, it has its risks and it will not always work out. The IG are just squishy mortals after all and sometimes they jump out, shoot/assault horribly, and die. When the platoon dies horribly why my hybrid list has a mechanized platoon that can grab objectives (often doing this while Al'Rahem's blob distracts the foe) and my all-infantry list has an emergency backup meltagun platoon in case Al'Rahem and platoon meet their maker.
Captain Al'Rahem of Tallarn: well worth his points (upgrade/astropath) if you use him carefully, have a duplicate objective-grabber unit or set of units, support him, and if you are playing a 2,000 points or higher game.
Tallarn Commander
IG, "We are many. They are few.""