Now that the word is out and SL gone, TT is always out of stock of what I've ordered for over a year without a hitch, I'm getting a bad vibe they are turning into another MM. It's a shame that every time I find a good IOP, they end up getting overwhelmed when the word gets out on these forums.
Unfortunately there are no guarantees with any IOP, vendor, etc as a lot of them come and go. The last two times I have ordered from T10 were also recent orders placed around the same time of the official "exit" of the vendor you mentioned above, therefore causing a sudden increase of T10 customer base. I don't know what it is you are ordering, but most of the time when I log in to their site, and something I want is out of stock, I just continue to check back frequently and then it is usually back in stock within a reasonable amount of time. I am sure the increase demand causes many products to run out of stock at a faster rate, but they are usually back in stock fairly quickly, and if you frequently check back, you will likely catch it when it is in stock again.
Also, have you tried to email them about what specific product you have ordered for over a year, that now often seems to be out of stock for any more information- as in maybe they are changing dosages, manufacturer, replacing with something else? That may explain why it appears to be ALWAYS out of stock. If it will be back in stock, perhaps they may be able to anticipate when that might be, so you know when to check for it.
Considering the increase of customers they have recently acquired- from the positive reports posted by other members and my own personal experiences, they continue to do an excellent job with maintaining quality customer service, order processing, shipping and quality packaging.
Again, there are no guarantees with whoever you use. However, I haven't seen anything at this point that indicates they are going in a bad direction, and being out of stock of certain products at times is not all that uncommon and can happen with any vendor. Things like decrease in quality of product, packaging, communication, people not receiving orders are the trends to watch out for.
For right now, they continue to be very reliable, and while this is the case, there is no reason to not continue ordering from them IMO.. Of course, if you do not feel comfortable ordering for any reason, then absolutely do some research and find one that you are comfortable with.