I'm usually riding my hybrid Giant Roam but recently I've been given a 2nd hand Decathlon 27.5 MTB for free and I've started hitting some mountain bike roads (not trails, more like forest paths, fire paths etc). I was pleasantly surprised to find that the bike is a perfect fit for my body type, like 100%. It is easily controllable, comfortable, compliant. However, it's old, not worth maintaining or upgrading, and unbearably heavy. With this in mind, I started a search to find an entry-level trail MTB and since I'm familiar with Giant I looked at their Talon models (Going to a better one in Decathlon with the same frame geometry is not an option since they are all sold out and no-one knows when restocking will happen).
Unfortunately, I'm in between sizes so not an easy choice regarding the size. Ideally, I would like to find something that has 100% the same fit as the current one, so I started comparing the geometry tables to find out which is a better match (due to availability, the bike might be ordered online so no chance to test it in advance :/ ).
Question is, is it safe to assume that M's geometry is as close as it gets to Rockrider's one? Do you see a point where Giant would be completely different from Rockrider?