Next Step... Manhattan Challenges/Archives or GMATclub chal?

Ok... So as I round out the OG I find that I only have a few areas I can identify as weaknesss. I am going to the Manhattan Word Translation book to work on those areas. I already found their number properties book to be invaluable... I have challenges from their site for free as a result of buying the books but some on here are saying they are impossiby difficult and not too GMAT like. Others have stated that they are easier than the GMATclub challenges, assessing their questions at the 42-46 level. Can some one give me a run down comparision of MGMAT challenges v. GMATclub challenges. And are the MGMAT archieves different than the challenges. I am currently scoring all over the place depending on the practice provider for quant. I got a horrible 36 in a Veritas practice test the other day and a 40 on the 800score, last week I got a 42 on Thomson/Peterson. I got a 42 on the real GMAT back in March on first attempt. I can't imagine that it would be lower now seeing how much more I know about number theory, geo, and some other core areas. My current weakness lies in rate/speed problems but I think the Word Translations will shore that up. Seemingly regardless of the test's level of difficulty I seem to be getting 15 questions wrong. Any thoughts would be appreciated. I know I keep going on about quant... But when you are getting a 97 percentile in verbal... a poor quant score is very irksome.