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I have had the Meade 4000 #140 apo, the Orion Shorty Plus and an Orion Deluxe equivalent 2" Japanese barlow amongst many others. Barlows are hard to get right: Orion Deluxe 2" aka UO 2" is the best I've used, TV 1.8x second.
I've seen a few examples of Meade #140s. At best they are good optically but need a bit of work (barrel blackening) to make them perform well. At worst they have bad astigmatism and are useless (the one I ended up with and still have is like that). IMO they are not worth it unless cheap and you know how to tell a good barlow from a bad (defective) one and buy from a dealer who will refund.
Re meade 4000 Plossls, I don't think the current crop is any better than the GSO Plossls, which are quite good already. Comparing my 25mm GSOs with the 5-element Antares Elite (top of the range Celestron Ultima style) plossl at f/5, they perform similarly. They both show about the same amount of astigmatism on bright stars in the last 10-15 degrees. The Elite has a more even illumination of the full field. The GSO darkens a bit towards the edges. It is not a big difference but it is fairly obvious to me and does make the FOV feel narrower in the GSO, although it's virtually the same.
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