Welcome to crypto where there is no way to predict anything.  Dare I remind people on the forum that were were looking at $650 BTC last year?  Just as fast as a bull market comes so does the BEAR MARKET.  If you have a time frame of multiple years and are not in a hurry to get profit then crypto might be for you.  Right at this moment we are seeing a strange blow out on BTC and the markets have been mostly bullish since the beginning of the year.  So we see a lot of people chasing the market.  Not sure that I would price anything based on todays values.  

I would say as long as your patient and are willing to work through the insanity of the wild fluctuations and play your cards right I know some people here on the forum that have done very well for themselves.  So I try to follow their example.

How long will this equipment last?  Honestly if Inno were to price match or even get close to price matching Bitmain with the A5 we could all be forced to upgrade our gear by the end of the year.  That kind of hash rate and efficiency would force everyone to upgrade.  It is a risk if you buy the D3 that the Pindea, iBelink, or Inno folks who are making a more efficient miner could take the fight to Bitmain in pricing.  Their more efficient rigs would make the D3 old news very fast.  The only thing in Bitmain's favor at the moment is price.

So how long will your investment be good?  It may be a bad investment right now if any of the other manufacturers decided to challenge Bitmain on pricing.  Hardware cycles tend to reflect profit.  If there is profit to be made then there is hardware coming to market and it can be an endless cycle and you may not ROI on the gear.  When the profits are little or none then the hardware market dries up and your investment may last a lot longer, but the profits are really thin if anything.  So the fact we see hardware showing up just means it is profitable at the moment.  It also means that new hardware can quickly appear that makes your investment obsolete very quickly.  Right now we already see equipment announced that makes the D3 obsolete if not for price.  So buckle up it could be a bumpy ride.

New people only see the "right now" and think this is the norm.  Even some people who have been around for a while quickly forget what mining was like 12 months ago at this time.  Then everyone acts shocked when the markets do what markets do, there are rises and falls.  Are we going back to $650 BTC?  Maybe, maybe even lower, maybe much much higher.  There is no norm in crypto.  

Time and difficulty work against us.  So I don't think anyone can afford to wait for Inno to drop price.  If they do then great add some A5's, but until then your best bet is to add hashing power as quickly a reasonably possible.

X11 is going to get crushed with all this hashing power as it is.  Only the first miners online have the best shot of a reasonable ROI.

The price to performance ratio is WAY in the Bitmain column at this point.  Inno has to reduce the price to make this more appealing.  At some point in the not so distant future only the most efficient and hash dense miners will survive, but at this price point I can't recommend Inno. 

Inno is a good company and good people.  They are an electronics company that make a lot of different things.  They do not specialize in miners, but they have proven themselves to make pretty good miners in the past. 

The people there are good to work with, but due to their size and scale it is nothing like dealing with Bitmain.  At Inno you will be working with people, the process is somewhat manual when ordering, and they do back up their product.