I'm not sure that there are really any improvements on MB designs either.  I have a set of MB's (non-Titleist) that are 9 years old in March and have hit most new styles and haven't seen any change besides cosmetic.  Looking at the new 710's just because I might be playing amateur events this year (grooves), finally.  By no means am I a tech guy, I don't even re-grip my own sticks. Most advancements are in the cavity back styles.

That's a great question.  Nick and I spent some time with our R & D iron team asking them about designs, shapes and looks and the short answer is, yes - there are real performance changes in the muscle back iron designs.  Making changes such as sole shape changes the way the club feels at impact and how it goes through the turf.  The weighting of the actual muscle portion will affect where the "sweet spot" is and they can make it feel more solid on off center hits or give you more feedback (depending on the design).  The shape of the toe, the top line or the amount of offset can make it easier to hit and/or more forgiving. For example, based on feedback from tour players, our design team created the 710 MB's to interact with the turf better and give better feel on hits that were higher on the face (out of the rough).  It is not drastic, but for players that like the feel of muscle back irons, there is a distinct difference. 

I played with 2 different sets of blades for ten years.  Tommy Armour 986 Tour, and W/S FG51s.  The first round I played with my Titleist 695MBs was very impressive.  Fitted with S400 Sensicore shafts, the feel was incredible.  Sweet spot was far more solid than my previous sets.    Ball flight was high and true.   My 2 iron is a 695CB fitted with a Project X 6.5 Rifle shaft.   I agree with Cathy and the R&D staff, even though they are talking about the 710s,  there's more than meets the eye when it comes to Titleist MBs.

Deno

Going from TA1's to the 710MB's hopefully this year, I noticed the loft and lie is one degree stronger in the 710's.  How is that going to affect the ball flight? Lower and a couple yards longer? Couldn't find original bounce on the TA's. Easy fix to match old lofts hopefully.

Thanks.

Yes and No is your answer. Cathy gave you the right answer. the only thing manufacterures dont like is the USGA has so many rules governing bounce of club face is that its very hard to make a perfect center hit go farther but they can improve off center hits and player comfertability with the club. What i like about Titleist is they dont make new equipment every 6 months like some out there  not saying any names but a certine allegid "number one driver" company relesed over 8 new drivers last year alone and has already relesed 4 this year claiming there better than their own last year versions.

Ok enuff about that Titleist dose post USGA club restrictions informatioin on its site so if you read about it you'll know what im talking about when i say there are some things they cant improve on but yes they can make a better club from year to year Just dont expect life changing improvments your not going to gain 50 yards on a perfict shot. and i'll prove that to anyone. I have some good old Jack niclas edition Mac Greger blades i can hit a 7 iron almost the same distance on a perfict hit. but Its the of center shots that dont come close. and thats the proof in the pudding you can grab a 80's model iron in almost any used club store now days and try this for your self even comparied to your current irons. Hit one off the toe of both irons and compari the yards. and be honist with your self how many of us on this web site hit perfect shots every time. it never hurts to improve your bad game if you know what i mean. Titleist tends to put some good thought in to each improvement and they reliy on loyalty and quality of their products to get sales. Not Making something new just to make it new. Bravo titleist.

The biggest change for me is not the club itself, although i can feel some differences with the weighting, but it is the shaft options available now. For me that is the most critical part, i could almost any head but without the right shaft it really wouldn't matter what was on the end of it. Having said that the 710MB is the best of both worlds, great shaft option and incredible feel from the head..