I am looking out to buy a gyro+rudder servo for my upcoming Raptor 50.  Options in front of me are :
Futaba GY401 and the Thunder Tiger one. Spartan is too expensive for me at this stage.
Which one is better for me ?

Lots of choices these days.  The Align GP750 works great with an Align DS620 servo. 

If you are keen on Futaba, the new GY520 has been great (per couple of people on our field).

I have found TG7000/DS0606 to hold better than GY401/9254 on a Raptor 50. This was a while ago doing mostly sport flying. There were a few maneuvers I could get the 401 to blow out consistently and TG7000 was locked in through the same maneuvers.

I'm GP750 with DS0606 on my atom and it holds really well. There are some reports of GP750 not liking the vibrations on a nitro heli, but no personal experience here.

I know couple of people using the GP750 here without issues on 50 size helis. Will check with them if they had to do anything special about vibration (like which double-sided tape / pad they used for mounting the gyro).

Forgot to mention. I fly my 50 size heli with a "Logictech 6100 gyro/servo combination", and so does one more person on the field.  If you are willing to spend in that range, either this Logictech combo or the Futaba GY520 with an Align or Futaba high speed servo will also be good choices.

Sorry for breaking the discussion, I have read a lot of good reviews on the HK401B for just 13.99 USD, I have used it myself and Its simply great. Y do people still use the original futabas and aligns?

Use on a 50 size and a smaller size are different in terms of performance.  Plus, what you are doing is hovering.  Try doing some serious 3D, and you can tell why some others cost more

Yet another reason is that a Google search about using this gyro on bigger helis hardly brings back any meaningful results    Not that we have to overspend !

Ya you are right, better not spend less on gyro and break a bigger expensive heli. Adarsh was very positive about the futaba gyro when I asked about it.

Guys,
How is the Spartan DS760 Gyro ? Anybody used this one ? how does it compare to the GY520 ?

Spartan DS760 is considered the best by many.  One flyer on my field has it, and has only good things to say about. Prize, as you can imagine, is on the higher side too. 

My understanding is that it is considered one notch above the GY520, but then GY520 users have made it clear that they see absolutely no reason to consider anything else !

Hmm. I am getting it at a decent price of $149 at hobbyking. thats why got suddenly interested in this one. I think its going to cost me the same as a GY520 so i might consider Spartan

I just noticed that Spartan has an even newer model named "Quark" (actually had seen an Alan Szabo heli 3D video with it, but forgot about it).

And people are saying that it is very hard to differentiate between the DS760 and GY520. Looks like you cannot go wrong with any of these, so price/availability may be the key.

I am sorry LHS,
I just coudnt resist Hobbyking's offer if the Spartan DS760+Futaba 9254 at USD 230. Just went in for that. Now i hope it comes through alright via the EMS.