I wouldn't touch either of those guns with a ten foot pole. There's tons of examples of LWRCi guns having to go back... Pat Roger's batch, etc.
They've even failed on the Military Channel shows. I watched the goofball from LWRC hand cycling every round on one of the shows.
And you are whom exactly? Any experience dealing with the rifles yourself or are you just another internet keyboard commando? Disclosure: I was the VP Operations for LWRC until about 3 years ago when the company was bought out and moved from VA to MD. I know what the rifles can do and many of the issues are as a result of 'growing pains' of moving from less than 500 rifles a year going out the door to over 10,000. With growth like that, problems will occur from time to time. What matters is how they are handled and it seems that the current management at the company is truly interested in taking care of the customer's issues.
Now, having said all that, I wouldn't buy a piston gun for what the OP says he wants to do with it. Sure, piston guns run a lot cleaner (I have an original LWRC gun with over 16,000 rounds on it without cleaning, much of it full auto) but for 'regular' guys, DI guns will, if built properly and lubed appropriately, run as reliably as piston guns.
Folks are free to spend money as they choose but for the price of one LWRCI .308, I could buy a similar DI gun with at least 2 other complete uppers in different calibers such as 7mm.08 or .260 or .243. Go crazy and buy a lower and two other uppers in .300 SAUM or similar and buy a crap load of ammo for it!
As far as 6.8 is concerned, I think I was the first person in the US to shoot a cow elk with one about 5 or 6 years ago but I might be wrong. It is a great caliber and again, just go buy a DI gun and spend the difference between that and the LWRCI on ammo. Best ammo to buy is made by my good friends over at Silver State Armory in Pahrump, NV. Silver State Armory manufactures and sells 6.8mm SPC Ammunition and custom brass cases, 5.56mm ammo, .223 Remington, 7.62mmx51mm ammo, .308 Winchester, Bullets for sale
Piston guns excel in shorter barreled carbines (10.5" and below) or when lots of full auto and/or suppressor work is anticipated. If I was heading overseas into combat, I'd surely want one.
If you are stuck on a piston gun, Ruger make a very nice product as do my friends at PWS. http://primaryweapons.com/store/pc/tactical.asp The Ruger in 6.8 is slightly flawed in that it does not have the Spec II chamber or a 1-11 twist rate that will get the best out of the round but other than that, it is a great rifle for the money.
Other than my already disclosed connection to LWRC, I have no interest in any other companies I mentioned. POF is a company that has made great strides forward over the years but based upon my own experiences with the rifles, I cannot recommend them as I have seen too many issues arise with the basic design.
Choose wisely grasshopper!
FYI: lest anyone be doubters of who I am or what I say, here's a couple pics of me and my cow elk. These pics are also on the SSA website and used to be on some other forums years ago.
You mention the Military Channel: were you there? I wasn't for the last program but prior to that? Well, you be the judge......