Well, Brandon, I own acoustic guitars by both manufacturers (although 2 out of my 3 electrics are Epiphones), so I can shed some light on my experiences.
My best Washburn is my D61SW, MIJ just like your D64SW. It is heads and tails above every one of my Epiphones in respect to lutherie, tone and playability. Having said that, though, I must admit the only Epiphone acoustic I have right now is an AJ10, a low priced all laminate guitar I use for camping excursions, so there's really no contest, now, is there. That is due to change soon, as I have an Epiphone AJ500RC on its way to me via FedEx as I write this, one of Epiphone's Masterbilt line of acoustic guitars, and once that gets here I might have a better chance to compare it to one of my Washburns. However, knowing how well my D61SW is made, I doubt that even that would be fair to the AJ500RC, so perhaps the WD32SW might be a better comparison, both are about the same size and both are all solid wood guitars, so soon as the AJ gets here next Tuesday I can speak to build quality, tone and playability as I compare those two.
As for comparing your D64SW to your friend's LP Custom, it's like comparing apples to oranges--there's just no way to compare them as they are so different. Electrics in general to tend to be a bit easier to play than acoustics, but I've played acoustics that are quite easy to play, too, so that's a generalization and not a rule.
And, oh, let me clue you in on Pike--he's sort of the historical guru here on the Washburn forum, I've said it before and despite his modest response to the contrary, I'll say it again--Pike has forgotten more about Washburn guitars than most of us will ever know, with perhaps the exception of jsmithjr., who has an incredible collection. I mention this so that you'll realize that if Pike says something, you can take that to the bank, he's just that good.....your friend probably recognizes a very well made guitar and is badmouthing yours in hopes you might give it up someday. We both know you would never do that out of respect and fondness for your grandfather, but that can't keep your friend from hoping, now, can it?
Stay the course....you'll be much happier with your D64SW 20 years down the road than your friend will be with his LP Custom, believe me!
YerDugliness, Esq./Post No Bills
Guitar Playin' FOOL
Retired & attempting to age disgracefully!!!
Washburns: WD32SW and D61SW
Epiphones: a Dot '63 ES335 repop, Masterbilt AJ500RC (shipped 10/23/08!)
Yamaha Classical guitars: G231-II and G60A
Hippner #506 concert grade classical (arrived damaged, repairs underway)
Takamine 2005 LTD Edition
Breedlove custom shop Deluxe Build Revival 000 slot-headed 12-fretter
A Hohner classical I left at a vacation home in SW KS.