I would recommend getting the Field Manuals. There are new weapons and mech variants in them. The only catch is that after the Draconis Combine FM they switch from mechwarrior 2nd to mechwarrior 3rd edition rpg rules. Also they focus on roughly 3050+ history and more militarily orientated. Coming out IIRC the end of the 1st quarter of this year are rewrites of the original House Source books. The new series starts with House Stiener. This might be more what you are looking for, if you want more of the economic, social, and eduactational information. Also coming out around the same time is a War of 3039 source book which looks like it will be really cool. If you are interested in more new releases goto the New Release section of ClassicBattletech.com.
As for the comment that the 2750 book was just like the 3025 book, it depends on which 3025 you have (before or after the unseens we removed). Also if you look at it, the 2750 book mechs are for the most part different variants of the mechs. 2750 are more advanced techwise. There are er weapons, xl engines, and double heatsinks. For instance tthe Flashman in 2750 has 15 DHS, an XL engine goes 5/8, and has an Antimissile system. The 3025 Flashman has a standard engine goes 4/6, has no AMS, and has 23 SHS.