7.Nd2 Bb4 8.Qc2 Ne4! 

This move avoids most of the extensive theory in the 8…O-O main line.  After 8…O-O in the main line, white could play 6 or 7 reasonably good moves, and black would need to know how to handle all of them.  For example, 9.Bxf6, 9.Be2, 9.a3, 9.Nb3, 9.Bh4, 9.cd5, 9.Rc1, 9.Bf4, and even 9.h4 or 9.c5.  This is too much for me at my level and with my limited study time, so I go directly into a more focused and forcing continuation with 8…Ne4.  I don’t believe it is necessary for black to O-O yet.  I remember an old piece of advice from one of the greats (I forget who) that cautioned “castle if you must, but not just because you can” or something like that.  After 8.Qc2, black can castle, but that move doesn’t put any immediate pressure on white.  It feels passive, like black is simply responding to white’s moves, rather than making white respond to his.  One of the main line variations goes like this:  8.Qc2 O-O 9.Be2 dc4 10.Bxf6 Nxf6 11.Nxc4 Qc7 12.O-O ugh.  I’m not playing the Cambridge Springs to get a soft position like this!  Black probably has to retreat his bishop to e7 and white just gradually increases his advantage without having to worry about any counterplay from black.  Or, in another one of the main lines (perhaps the one you had in mind), black plays 9.Be2 e5 but white has 10.de5 Ne4 11.Ncxe4 de4 12.Rd1 Nxe5 13.O-O Bxd2 14.Qxd2 Qxd2 15.Rxd2 Be6 16.b3 f6 17.Bf4 Rad8 18.Rfd1 and here, in "The Cambridge Springs" by Krzysztof Panczyk and Jacek Ilczuk, the authors conclude "Thanks to his bishop-pair and domination over the d-file, White has a better ending."  I think that is an accurate evaluation.  I wouldn't want to play the black side in an OTB game.

In contrast with the passivity in the 8...O-O main lines, black can start immediate tactics with 8…Ne4!  Here is one likely possibility of how white’s play becomes limited and black seems to be forcing things:  9.Ncxe4 dxe4 10.Bf4 e5! (good now) 11.Bg3 O-O (this is needed now because the center is getting blasted open) 12.a3 exd4 13.exd4 Re8 14.O-O-O Bxd2+ 15.Qxd2 Qa6 16.Qb4 Nf6.  There is a lot of action that can be directed at white’s king position from this point.  A white player who would have felt comfortable playing against the normal safe main lines after 8…O-O would probably feel rattled here, thinking he had lost control of the game. 

Anyway, 8...Ne4 involves a lot less study time, I can easily remember the lines during an OTB game, and it puts pressure on white right away.  It may be that some of the 8...O-O main lines are just as good, but white has too many options along the way for me to contend with.

7.Nd2 Bb4 =   

In what line do you advocate that black play e5 as soon as possible?  e5 is generally not good for black.

7.Nd2 is just as good as any of the 4 or 5 main variations (7.Bxf6; 7.cd5; 7.Qc2; 7.Qb3; 7.Rc1).  I play the Cambridge Springs, and don't mind seeing 7.Qb3.  I just play 7...Ne4 and black is fine.  Same response works against 7.Qc2.  A lot of these line transpose or have basic similarities.  The exchange variation is no problem.  7...ed5 is fine and almost always transposes into one of the main variations.  But, black should not  play cd5, which gives white too much freedom on the queenside and doesn't help black's c8 bishop.

After 7.Nd2 Bb4 8.Qc2 Ne4 is already slightly better for black, and white has many mistakes to avoid, perhaps too many for most players under 2000.   Here's one example: 7. Nd2 Bb4 8. Qc2 Ne4 9. Bf4 Nxc3 10. bxc3 Bxc3 11. Rc1 Bb4 12. cxd5 exd5 13. Bd3 Nf6 14. Rd1 Ne4

I play the cambrigesprings.

Provided white doesn't chicken out and flee to the exchange var I play 8...dxc

Play could follow 9. BxN NxB 10. Bxc4 Nd5 11. Rc1 0-0 etc....

Over the board the Cambrige springs is a great opening.  It's actually sound unlike some of the off beat suspect openings club players play for shock value.

The problem is.......... white usually sees where your headed and will usually bail out with the exchange var.

All that knowledge/study time gone!

  Todays most d4 players are prepared for the accepted, the declined,  or the slave etc...but the Cambrige springs is off the beaten track far enouph where most don't want to go there and try to avoid it.

Hence, I don't get to play it as much as I wish..... 

Personnaly I might change to the Lasker's var.  It seems like it might be good because you can get into it fairly quick before white knows what your doing.   It's passive....solid but passive.......sometimes the better prepared has the advantage i.e. over the board.  I'd take a passive position that I really know over a position that's full of fire and unclear....(IMO)