I don't think that these programs are very important for HUSNG because the changes in blinds force people to change their style. Most of the people I know swear by HEM over PT, but I don't use either of them much.

HEM is a lot better than PT - it has a lot more stats plus the customizable popup-displays plus better filters etc., etc. - I used it a long time for 6-max cashgames and really liked it.
However, I stopped using it for HUSNG's about two months ago because it made me go on auto-pilot too much.  I've also fallen to the trap too often that people changed their strategy during the match and I didn't adjust properly because my HUD still had the old numbers.  This happend especially when playing more often against the same oppenent - once your HUD has statistics from 1000+ hands, it could take quite long until you realized that he's adapted to your strategy and changed his style.
My results have improved a lot recently when I stopped 5-tabling HUSNG's and also started to play without a HUD, thus focusing a lot more on my opponents - I'm now making more money single-tabling the $50's than I did before 5-tabling the $30's, and my variance also got down significantly.

First of all: you don't need either of them for HUSNGs really.
That being said, HM ist a lot better than PT3. I used PT3 during the 60-day trial (not for HUSNGs) and had a few issues like couple of crashes every now and then (not sure if it had something to do with the amount of tables I was playing) with some settings and configuring the HUD really sucked. PT3 looks a bit nicer better but that's basically all. I switched to HM then never had any problems with it. There are some nice features included that PT3 doesn't have and configuring the HUD was a lot easier.
Now I use HM only to track my results and to review specific hands in the replayer. I don't use the HUD for HUSNGs because it's not necessary (and maybe even a bad idea) and like I already said: I used these programs before I tried HUSNGs. I don't know if you like to spend money for it if you don't use the features. A cheaper program like the tourney manager is probably enough if you only want to track your results. If you are playing other games too (especially cashgame obviously) or are planning to do so, then I'd recommend buying HM. But you should probably give both a try - both programs have a trial period so make use of it. PT3's trial is very long (when it was originally released it needed a lot of bugfixing so they gave it a 60 day trial) but the 15-days of HM should also be enough to make a decision.

I use holdem manger and love it. Its great for keeping results. If you play cash and mtt's too its very good.
I do have the hud on when I am playing HUsngs, I don't really pay any attention to the stats but just love being able to see the mucked cards without keep clicking on the hand history, I find it helps me focus on the game more.
Some of the stats they have avaliable are pretty good now tho and some of them are certainly useful as a guide, but i would never base any desicions on stats.

Oh, the mucked cards are really a good argument for using a HUD, completely forgot that.
I'm playing on Absolute and keep the replayer window open while playing - on Absolute, mucked cards are shown in the replayer.

sorry to derail slightly - but whats the husng action like on absolute??
Seems like it could be profitable to play on there, but after the whole incident, I don't think I ever would just out of principle. But maybe my stubboness may be losing me value - dunno

They offer regular speeds with 10 minute blinds and turbos with 5 minute blinds, both start at 5/10 so you start with 150 bb - there are also ultra-turbos, but I don't like them very much.  I'm currently playing the $50's and $100's, both regulars and turbos.
The opponents are generally very weak, even at the $100's, and a lot more passive than on full tilt, and I really like the 150 bb structure because you have so much more time to outplay your opponent before the blinds get high - for instance I only get into 25/50 in about 1/3rd of my regular speed games, and into 50/100 in about half of my turbo speed games.
Unfortunately, traffic isn't very high and sometimes it takes a while to find an opponent - I've already waited 20 minutes or longer.  The software also isn't that great and you don't have much time to make your decisions, there is no timebank.  I only single-table at the moment, so it's not so much an issue for me.
My main reason for playing on Absolute was that I was really frustrated in March, I lost almost my entire bankroll on Full Tilt due to tilt and bad luck, so I wanted to make a new beginning and start from scratch.
They offer 30% rakeback plus a reload bonus every couple of weeks plus points for cash, so you get a total of about 35-40% rakeback, which is quite cool.
Multi-tabling never worked for me, but there's at least one regular 'blistexx' who's a 10% ROI winner according to Sharkscope, and I always see him sitting at a bunch of empty 500 chip ultra-turbo tables, so I assume he's multi-tabling.