ive always wanted to try out one of those bad boys
just wondering how they would feel
i really like the slow heavy ass riffs etc etc

feels oh so right in so many ways

sounds good

iso more input

They aren't functionally any better than a 6 string baritone tuned down a lot without an extraordinary level of proficiency, and they lend themselves to wankery either as super-low tuning guitars, or to show off things that resemble exercises more than music. They are rarely utilized for the actual extended range, and while a handful of extraordinary guitarists do amazing things with them, most could do the same thing with a guitar tuned down to F# or a full octave to E.
The most common use is percussive playing on the two extra low-tuned strings - Meshuggah and Dino Cazares are examples of this, as they rarely use the high end and most/all of these songs could be played on a six string tuned low.
Some bands, like Portal, just use the low tuning and don't use half the strings on the guitar, but they have a lot of noise (or "atmosphere" if you prefer) from the low tuning, and minimal clarity of the actual playing. Again, this could be done on a low-tuned 6 string.
Then there are the guys who come up with exercises that use all eight strings and call them music - Animals as Leaders is probably the most prominent, and while Tosin is an incredibly proficient guitarist, all he does is play circles around people who fell asleep listening to his "music" - complexity for the sake of complexity while completely forgetting the building block of most guitar-oriented music, the riff.

I can think of three players who have impressed me with their use of 8 string guitars, and all of them use one extra bass and one extra treble string:
Chris Letchford of Scale the Summit - uses both the treble and bass strings with an unusual approach to music, difficult to explain concisely.
Rusty Cooley - Top notch guitar wanker, but he's glorious about it and really uses the high and low ends and everything in between when I have seen him play an 8.
Alexander Vynograd - Classical guitarist who came out with a way to emulate the left and right hands of a pianist on guitar... this video demonstrates it better than my words can: http://www.youtube.com/watch?v=Q_tMjYxYTwA
I have not heard Ihsahn's latest album on which he uses 8 strings yet, I need to give it a listen.

I have played a few 8 strings, made by ESP, Ibanez and Sherman, and I didn't like any of them. It is difficult to find a compromise between lighter guitar strings on the bottom and using bass strings, or bass-sized strings, for the low tuning. The scale length is also a difficult issue to resolve, on a 25.5" scale, it's hard to find a compromise of action height, string size/tension, and tone, but on a longer scale length, up to 30", the top strings face the same issues and become difficult to play. Multi-scale-length/fanned fret guitars are not worth playing as far as I am concerned, there is too much to change about your playing for what you gain. Finally, I don't have any reason to play an 8 string, if I want to tune really low, I'll use a baritone, and if I want to tune an octave down, I'll use distortion on a bass - there are a lot of interesting options for using a bass differently, such as the 12 string (tripled 4 string) bass sometimes used by Jeff Matz of High on Fire.

thanks for the info.
but really tuning a 6 string to F#?
when i 1st bought my good guitar it was a LTD kirk hammet with a floyd rose on it
was a bitch tuning it to A and was really hard to find big enough strings to handle that where i live.

ive been having this 7 for 6 months now played with it and like it cause of the advantage i have with the extra B string or should i say A. Im still expenimenting with Low tunings trying to find one i like.
but yea i could tune the 7 to F# i would have to order some really thick strings. where i live they dont even sell 7 string packs. they had to give me a reg super thick 6 string pack with a extra high E packet on its own.
but thanks alot tho

Heavier strings on a Floyd are always going to be difficult, and fixed bridges are much better for low tunings - it is nearly impossible to find a baritone with a tremolo for a reason.

I order all of my strings online, I'm never really happy with standard sets. I usually play 58-42-30-22-15-11 tuned to CGCFAD, when I used to tune lower I don't think I could ever deal with a standard string set, and I hate light bottom strings so I couldn't deal with any standard 7-string set. While I used to tune really low, I have much better control over tone when I'm not tuned down as much, and the only time I tune really low (below B), it is because I want a muddy/sludgy sound. I find that heavier strings in low tunings also vary a lot by brand, SIT strings have the most ultra-low tuned clarity.

As long as you know how to set up your guitar, tuning really low with a baritone isn't hard, get the right strings for your tension preference and set it up, it'll be a lot better all around than an 8 string.

Your fatty 11's make my fingers feel like baby hands