Electronic room correction can be helpful. I know of at least three guys using the Parc from Rives Audio with good results. But I believe manual room correction, if possible, to be better as it keeps the signal path cleaner. Rives created the Parc as a worse case scenario solution. But its still best to start with an accurate speaker because you cant get any better than the source. The MBL is a curious comparison as it is pretty much the exact opposite of a Dunlavy from an engineering standpoint.
As far as crossovers go, Dunlavy would describe the parts he used as "adequate". Being a measurement freak, his opionion was that the exotic parts did not measure any better than the ones he used so he never used them. This is maybe the only area where I disagreed with him. And there are several people who have ventured a parts swapping upgrade on several different models with good success. I've done it a couple times for close friends. Swapping out caps and resistors has the greatest effect. This is fortunate since none of the coils have their values labeled and using handheld inductor measuring devices are not nearly accurate enough to maintain the precise accuracy of the original design.
But swapping these parts can be expensive because there are usually quite a few in there. And unless you have the expertise to determine the ones used for frequency roll off versus the ones used for impedance correction you may as well just replace them all.
There is a guy on Audiogon who posted a detailed description of replacing parts in his 4A a few years ago. Though I am unconviced that he did it correctly in the end.
Anyway, anyone wanting to contribute to an archival project are welcome. Anything, no matter how trivial, would be appreciated. All original credits will be used.
And to deandob, if you are serious about "modding" your Alethas send me a note and I can save you a lot of time by pointing you in the right direction to start.