Groovyisland: You know what the guy at the studio is gonna tell you, right??? "You need to use these players", & "you need to do this/that/other, to give your track(s) a pro sound"....When in reality, you can do a really good job with Bob, Greg, & yourself....
Of course, have Bob/Greg/both do your guitar (and/or bass....Greg's a kickass drummer too), & take those tracks to the studio & have the engineer/mixer put 'em in the song. I'm sure Bob/Greg's tracks will sound as good as anything they're gonna do for you, IMHO....
As far as that goes, Greg does an excellent job mixing too, just saying, myself, I wouldn't go spend thousands of bucks when you can probably get similar results spending a lot less....depends on what Bob & Greg charge you though...
I'm no "pro" or anything (far from it actually), but I did mix a 5 song ep for a band from Colorado a couple years ago. They sent me the tracks via Dropbox, & I did the mixes in about 2 weeks, working on it in my spare time before/after work. I charged the band about $300 total (I actually wasn't gonna charge that much, $150, but the guitar player sent me a set of monitors because he said I'd spent too much time working on his songs, so just guessing, I ended up with about $300 total....)...I'm really not saying I'm interested in mixing your songs, I'm just saying you can get decent sounding tracks at a reasonable price...But, if you wanna spend a bunch of $$$, it's your call....
I tried to listen to your clip, but it kept taking me to my own Soundcloud page, dunno what's up with that, but I'd like to hear your stuff....