Any modern band that comes close to Mahavishnu Orchestra ?

Try Steven Wilson. His latest album Hand.Cannot.Erase might be something that you'll like. His albums Grace for Drowning and Raven that refused to sing are also superb. Check out the song Drive Home on Raven. Wait for the guitar solo. If your system can produce deep base all of Wilson's albums have it.

The shorter, tightly composed pieces by the M.O. were often quite good, but the long wailing solos and jams were often boring and indulgent to my ear. I found early Al DiMeola to be more focused and tasteful.

It was the age of the rock n roll dinosaurs, and M.O. should take their share of the blame. On the other hand, we can thank fusion and the like for some of the fine musical genres that were born as a reaction to it.

Psag, I will be the first one to agree that many Mahavishnu concerts were very boring. I probably explored the entire youtube looking for those concerts. I'd say, of what I found one in twenty was great, the rest was not worth it. Same with 70s Miles Davis, by the way.
Al di Meola is much better on acoustic guitar. His 'Cielo e Terra' mesmerising album is a masterpiece, 'Hearts of the Immigrants' and "Kiss my Axe' are excellent overall. There are exceptions though: Egyptian Danza from 'Casino' and Gods' Dinner Music from 'Splendido Hotel' and a few others are excellent with him playing electric guitar.

psag---I feel the same way about Cream live. I saw them twice, and they played the recorded opening version of many of their songs, then went into really extended improvisational take-offs. The problem was that, unlike really good Jazz ensembles, wherein when one player is soloing the rest of the ensemble (particularly the rhythm section) plays in a supportive fashion, with Cream Eric, Jack, and Ginger would often all be "soloing" at the same time, walking all over each other. What a mess! Eric realized the error of his musical direction, he says, when he heard Music From Big Pink by The Band (which contains the finest ensemble playing I have yet to hear, in ANY genre). Eric told Jack and Ginger Cream was over.

I saw Jeff Beck after McLaughlin and the Mahavishnu Orchestra opened the show and I was blown away! I was there to see Jeff Beck and he was great but John McLaughlin just stood there in all white and blew everyone away! Blow by Blow was a great album but I was about worn out after the opening of John McLaughlin and the Mahavishnu Orchestra fusion! Wow!! Al Di Meola is great and how about Leo Kottke I have never heard anyone play like these guy's?  And if you want to listen to some Blues how about Buddy Guy and Luther Allison if you want to hear some great guitar!! All the young players chase the masters and try to improve the sound good luck with that! The 70's still rule when it comes to the super groups of any generation period.