My local shop carries DigiTech but that one hasn't shown up yet, so I will be checking it out just for fun and to satisfy my curiosity. I have yet to see a Beat Buddy, but have watched YouTubes on both. I think they could be fun for writing.
The only Boss drum machine I ever had was a Dr Rhythm in the late '70s? or early '80s. I always thought of the DR series as drum box vs the sample player types. I suppose I'm wrong on that count.
Michael

I've got both a SR16 and a SR18.  The 16, 31A is my "go to" for Country (mainly what I record).  The only dumb thing there is no factory 3/4 in the SR16.  I have a 3/4 that I got from the salesman at a local music store.  He uses a SR16 live (for many music genres) when he does a one man gig.
 
The SR18 has factory 3/4 programs.  It also has a bass line (can be enabled or disabled) but I haven't found any way to change keys with the bass (I can go +1 or -1 but that's all). 
 
Both units can be user programmed.  But, for units with factory programs the Alesis is my choice.

Thanks for that information, fireberd. Lack of 3/4 or 6/8 is kind of a deal-killer for me. Too bad, as I can find SR-16s on eBay or Craigslist for $40-60. 
 
I'm leaning toward the SR-18 at the moment. They say it has more percussion sounds, but I've yet to find a listing. Maybe you can tell me: does it have shakers, congas, tambourine and such? I'm looking more for ambient percussion than conventional rock/country beats.

I needed several of each and made my own for the SR16(but I play drums, too). The SR18 instrument list isn't on the Alesis site, though it does say the there is a percussion bank amongst the 500 sounds. It'd be nice if they listed them, but I suppose there are some video demos with examples of the perc stuff.
Michael

I haven't used much other than the country programs. 
They have a list that can be downloaded of what the factory programs are.
http://www.alesis.com/sr18
 
 

Thanks for that link. It looks like 474 to 481 might be tambourines? is that right?
 
After looking at that list, I went to the downloads/docs for SR16 and they have waltz patterns available for it as a download.
http://www.alesis.com/company/media2.php?download_id=WjZSNgNoBWsGbQJl
 
I might not get to load them and check 'em out right away, but at least that is an option.
Michael
 

I found a YouTube video where some dedicated soul patiently stepped through every single factory preset on the SR18. As expected, 95% of them are useless to me, but it gave me enough of a preview of the sound set to know it would do the trick - although I'll have to spend some time programming it first.
 
The local music store didn't have one to try, so purely on the strength of you guys' helpful information I went ahead and ordered it via eBay. $175 with shipping, plus another $55 for a dual footswitch from Sweetwater. I just happened to have exactly $175 in my pocket in gig money, so I'm only $55 in the hole.
 
Now to work up to something I haven't done in 20 years: a solo gig. It's just background ambient music for a fundraiser and only for a couple of hours. Pay is crap but every little bit helps - plus they'll have food. I'll be lining my pockets with Ziploc bags in preparation.

LOL      I used to tell old pals (on the phone), that "the gigs in Vail CO, were pretty nice because of the food and bathrooms!" The pay was good, too, but the rent was very high and I got very (as in really very in the "most"way) tired of playing Margaritaville! I quit/left when a drunk stopped me while I was playing it. He asked if I knew any Buffet. I said like Margaritaville? (the crowd was roaring) He said, "yeah!" I said, "sure!" and thought that's IT. I am outta here, and I was. 
Hope the SR18 works out for you!
Michael

It's interesting this topic as I have found that over time less and less equipment, hardware, is made that would serve the solo performer. The first generations of drum machines had footswitches, only Alesis seemed to continue with that. Roland totally screwed up. My old 505 might have been the last of that generation with footswitched  start /stop. The Boss series required hands on. The sounds got better but they stopped marketing to solo performers in the early 90's.  Digitech stuff is built like a toy and would probably break in live use. 
 
The other option is using a USB footswitch and macro your laptop. 
I use a Xkeys footswitch for playback control. But you can start and stop Sonar with your foot. Trouble with Sonar is you'd need a big controller knob for tempo. 
I still use my 505 for quick beats. 1985 and still works 100%. 
 

When I first bought my SR-16 I asked Alesis support about a 3/4 program.  I got some instructions from them on creating a 3/4.  It was horrible and unusable.   Thankfully the young guy that worked at a local music store was into programming it and allowed me to copy his (useable) 3/4 program (and several others).