I've been playing bolt-on Ibanez 7-strings for a long time now.
The major difficiency on these guitars is usually the pickups.
And - there are TWO problems with the pickups:
1. They suck.
2. They are direct mounted.
I don't know who decided that direct mounting the pickups would give you better low-end or whatever the fuck the Ibanez ads in '97 said, but it was a fucking dumb idea.
Direct mounting puts the pickup as far away from the strings as possible giving you a hollow sound with nowhere near enough bite.
A quick and dirty solution to get better tone on these guitars is to take out the pickup screws and wedge something under the pickups to get them up higher, then reinstall the screws.
Go ahead and laugh, but in a pinch I raised the pickups on my first 7-string by jamming a bunch of Q-Tips underneath of it since they fit and there was nothing else handy. That's an instant tone improvement.
A better solution is to get yourself some humbucker rings and mount them the way they're supposed to be done. I'm sure this is why a lot of metal guys seem to favor the LTD 7-string designs. They're the same crap wood as the low-end Ibanez guitars, with a pickup that's no better than the stock Ibanez junk, but the fact that the pickup is closer to the strings gives you a better sound.
The best solution would be to replace the pickups with something which actually has some balls to it. And here's where I think a lot of people go wrong when they're playing the styles of music that are being discussed on this board.
You can't read a guitar magazine or guitar forum and listen to what these people are telling you is THE BEST PICKUP IN THE WORLD or THE BEST TONE EVER because they might be right - but they're talking about a totally different world. Blues and rock guys can get away with putting a Tone Zone or a Duncan '59 in a guitar and have a great tone that works in their situation.
But, if you're trying to play our brand of heavy music, the midrange boost on that kind of pickup is going to ruin your sound. It'll never cut through the mix right and it will never sound like you want it to.
Look for something which offers a good output level and CLARITY. The clarity is the most important thing so that you get good note definition when you're playing through a high-gain amp. You should be able to hear the notes that make up each chord rather than a big buzzy lump of sound.
I personally achieve this by using DiMarzio pickups. I have the Steve's Special in my 6-string guitars and the Blaze in my 7-string guitars. Both of these pickups are very closely related. They are actually closer in sound to each other than comparing a Tone Zone to a Tone Zone-7.
They have a very high output, which drives the input stage of your amp very nicely (in fact, I have never had to use a Tube Screamer or anything of that sort...) and the midrange is scooped out to give you the note definition.
By nature of design, to make a pickup louder you wind more wire around it. By winding more wire around it, you increase the midrange boost as well. These two pickups avoid that by using different windings on the two coils so you get high output without the muddy shit that comes from the mid boost.
And before anyone starts - I know the prevailing preference on this site seems to be for EMG pickups. That's fine and dandy - but if you've never tried anything else and you're using the EMG's because Loomis & Dino use them, or because Jaymz & Kirk have been using them forever then I highly recommend you try a few other things before you are absolutely sure what's for you. And that even goes for the pickups I'm recommending. Try them out. See what you think. Then try some more.
There's going to be something that gets YOUR SOUND out of your guitar and your amp, and it might not be the same thing that everyone else is using.
As far as trying out what I'm suggesting - swing by one of your major music retailers. Guitar Center... whatever... They usually have an Ibanez Universe hanging on the wall.
The Universe is a basswood body just like all the cheap Ibanez-7's out there. It's a maple neck, also the same thing. It does have a much nicer build quality than the Korean junk, tho, and there is a Blaze pickup in the bridge position. The pickguard serves the same purpose as a humbucker ring - so you can hear what a non-direct mounted pickup can sound like. Plug it in and let some of your riffs rip - hopefully through something like your normal amp. Or run it thru an HD-147 on the 5150 setting...
You can bitch about bolt-on necks and cheap wood all day long, but in the end the one thing in your guitar which has the single biggest affect on your tone is the pickups. Take the same guitar with the same neck and the same pickups and bolt it to a basswood body. Call that tone "A." Now, bolt all that shit to a mahogany body. Call that tone "A-1." The general character is still the same. The mahogany body is going to give you a tighter, brighter sound while the basswood is softer and rounder with a bit more low growl.
The tone is 95% the same on both guitars due to the pickups - the wood can change some of the characteristics, but they are minor in comparison to the changes you get between different pickups.
Sorry for writing a book - I just don't want anybody to think they can't work with what they have. In the end it's all music and you should never put off creating and playing to wait for the day when you have some kind of "better" gear...
ryan