Simon, don't let Sarge scare you...but I know what he means .
The Orchestra S is a very high quality harp. Honestly, with all the variety of harps I own, if there was a zombie apocalypse and I was forced to take just one family of harps, I'd take the Seydel Session Steels of which the Orchestra S is a member. The Steels have all of the best qualities in a modern harp: stainless steel reeds, full length covers tapered at the ends, a plastic comb into which the reed plates are recessed. Excellent comfort and excellent quality (check out my photo album, all my harps are pictured including the Orchestra S from Sarge).
But I get what Sarge is saying.. The harp sounds great but the unconventional tuning has a learning curve. For a beginner, it's a problem of learning a two note arrangements and, if you use tabs, there is very little posted on the 'net. I found I could START with an available tab but I'd end up having to "re-tab" about half of it. It's a big challenge for something that you don't really need that often.
However, take comfort in knowing it's an excellent harp but it might be more useful to you down the road when you are more practiced with standard tunings. You don't want to bite off TOO much right now.
I have an "F" song ready and a "Song of the Month" ready but I'm trying to find time to record them. As I mentioned once before, the climate in this part of the world makes summers insanely busy. We can't do much work outside during the winter when it's -35C so everything builds up waiting for summer(high today about +30C): house painting, concrete repairs, gardening, cutting the grass weekly, fixing the roof...
It's easy to find recording time in January. Not so in August.
Fortunately, there are plenty of good harp brands and models and as long as you don't buy a cheap, no-name generic, you are more likely to get a good harp than a bad harp.
I share John's disdain for the standard 1896 Marine Band with the wooden comb. I have 2 and they sound really sweet. But the old-world construction can be problematic. My background is in the maintenance of mechanical devices. When I see something, I not only want to know if it functions, I also want to knows if it is easy to maintain and repair. I love the tone of the MB and the only harmonica video on my facebook page is me playing a MB. But it is a S.O.B if something goes wrong and you need to open it up.
I will note, however, that Hohner makes a Marine Band Deluxe which is bolted together and has much better sealing. Seydel makes the 1847 classic which is bolted and has a well-sealed maple comb. Finally, Suzuki uses rosewood on some harps and they are very nice.
Specifically to the question of which "G" harp you should buy; there are excellent models in many price ranges.
In the less than $30.00 range, the Suzuki BluesMaster is a no-lose proposition. Personally, I think the BluesMaster is the best value in the harmonica world. It's comfortable with full length covers. The reed plates are recessed in a plastic comb so it will never hurt your lips or tongue. Construction is all bolt together so the thing can be taken apart in a minute or two. I can't think of a reason NOT to buy one.
As previously mentioned, the Hohner Special 20 is excellent. It's the first harp I ever bought. My only gripe is that Hohner prices have gotten a bit out of line. Here in Canada (god help us) a Special 20 which used to cost 10% more than a BluesMaster is now double the price of a Bluesmaster. So the SP20 is terrific but be aware of the value for you dollar in your market.
Like Keith, I love the Seydel stainless steel harps...though, I would avoid the "Orchestra" model for a beginner. I got an Orchestra from Sarge and it's glorious but the unconventional tuning will be a problem for a newbie. But the normal Seydel Session Steel is absolutely magnificent. I t has all of the best qualities of the previous harps with a plastic comb, recessed reed plates and bolt-together construction. It adds stainless steel reeds and and exceptionally comfortable cover plate design. The only downside is that its a more expensive harp. In the harmonica world, the Seydel Session Steel is a Cadillac...it's not in the Rolls Royce price range like a Suzuki Fabulous but it's pricey. But if you want to spend the money, you will be delighted.
If you want to try something out of the ordinary at a decent price, try a Suzuki Promaster. The Promaster has an aluminum comb. It's a very nice harp and it is much cheaper than other metal aluminum comb harps.
If you want to really go "out there" with something really unconventional, try going to amazon and finding a marketplace seller dealing in the Tombo Aero Reed. Aero Reeds aren't normally stocked in North America but you can get then cheap from Japan. They are beautiful harps with a chromed aluminum comb. I have several. You won't get a North American warranty but I've found them to be absolutely trouble free. When imported directly from Japan, the high end Tombo Aero Reed can be had for less than a mid range Hohner.
Lots of good choices.
Check out my photo album here. I have pictures of all these harps.
I'm sure I've recorded this before...somewhere. I'm getting old and I lose track of things . This is EIGHT DAYS A WEEK and it's a "live" recording for those who forgot how good-looking I am!