I have, and must say to start off that it is very important which cab and speakers are used in the comparison. I used a reissue 4x12 Marshall cab with greenbacks. The amp was a mid sevenites 50 watt JMP with EL34 power tubes. My Mod 50 had the stock Sovtek 5881's, which I like as an all around tube that is very durable. They were very close in tone, and arguably with a band in a gigging situation the average listener would not be able to tell the difference. The Egnater had more gain on tap, slightly more compression, but was able to get a great classic gain at lower volume levels due to the modern master volume and gain controls. Also the second channel of the SL module made soloing volume adjustments tonally transparent. When using a single channel amp and the volume control on the guitar to go from rhythm to lead, you loose gain and top end cut when lowering the volume for rhythm tones. The Marshall was slightly more open sounding and touch responsive, but it had to be cranked to get the goods. When the egnater was cranked it sounded excellent as well, but nothing was lost tonally when playing rhythm because of the two channels.
Although I slightly preferred the wide open tone of the Marshall, the versatility of the Egnater won out again. I suspect if I used good EL34's in the Egnater it would sound even closer. The only way I would choose the Marshall to gig with is if I had two of them, one for rhythm and one for lead, an amp tech and a roadie...also, I would have to be playing in stadiums as very few clubs would let me turn them up to get the goods.
If you are a gigging musician, trust me the audience wont know the difference.