Dubious I guess...

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Note added at 14 mins (2009-07-21 19:29:49 GMT)
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Cannot but agree..... Sorry)

Or: This may be so in some instances, but it is not true overall.

it might be true in some cases but in others in might not be
My English teacher from GB always made fun of the Russian phrase used by the Russian students during the exams translated as "I agree with you, but..." The teacher was furious! He wanted to know for sure for sure, whether the student agreed with him or not. The asker's phrase sounds to me as one of the same kind. That is why, I think it is beter to avoid the Russian logical ambiguity in this phrase, which pretends to be a politically correct phrase.

"On the whole this is [I/we find this] difficult to agree with [endorse] (as a universal [blanket] assertion [statement / characterization]), although I/we accept [agree / can agree] that it may be true in some cases."

Where square brackets denote different options and () is an optional insertion. I would say a lot depends on what "это" is, and who's talking - another researcher, a commenter at a conference, or what.

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Note added at 18 hrs (2009-07-22 13:28:13 GMT)
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With some concern that I may be taking the bait of a troll, I'll clarify my suggestion by writing out 1 or 2 of the options it contains, since it received a "disagree" vote based on the opinion "too detailed" (!) (with the grammatically inscrutable elaboration, "but if you are to explain - that sounds fine"). So, just in case:

"On the whole this is difficult to endorse as a blanket statement, although we can agree that it may be true in some cases."

"This may be true in some cases, though it is difficult to accept in broad terms."