What do you guys think of the Lock/cake double up SNG's.

either 10 man or 6 man, play till 5 or 3. double your buy in on cashing.

Are these good to MTT grind? Seem very good to me just have to get in top 50%

What would you prefer 6 man? 10 man? does it depend on your play style.

HUD preferences. Also i would like to get a hud what one is good right now?

Sometimes referred to as DoN (Double or Nothing) games, double ups have only one table, so they are are STTs (Single Table Tournaments). They are not MTTs (Multi-Table Tournaments), which start with more than one table. Do not confuse MTTs with mass multi-tabling, which is the playing of a lot of tables simultaneously, whether they are tournament tables or ring game tables.

For strategy discussion on DoNs, you should be reading the STT Strategy Forum. Just getting in the top 50% is not as easy as it sounds, or we'd all be playing them. Furthermore, if you are not already aware, this format is highly susceptible to collusion, that is, teams of players who all know each other and are working together and playing soft against each other to deny you a top half finish.

If you're still set on playing these, nobody can tell you whether to play 6man or 10 man, that's a decision you have to make for yourself.

The leading publishers for HUD software are Poker Tracker and Holdem Manager. Searching the 2+2 forums and using Google will help you learn more about them. They both have extensive websites and they each have a well-attended support thread here on 2+2 in the Commercial Software forum.

Good luck!